jjP Hi DUKE UNIVERSITY MEDICAL CENTER LIBRARY HISTORICAL COLLECTIONS Gift Of Anonymous Donor rk— - ■ - ■■ ■ — rf i Digitized by the Internet Archive in 2015 https://archive.org/details/elementsofgenera01gerb ELEMENTS OF GENERAL ANATOMY, NEW PUBLICATIONS TO BE HAD OF H. BAILLIIiRE, 219 REGENT STREET. NATURAL HISTORY OF MAN, By James Cowles Prichard, M.D. F.R.S. M.R.I.A. Corresponding Member of the Institute of France. Illustrated with many coloured Plates engraved on Steel, and interspersed with numerous Woodcuts. London, 1842. OUTLINES OF COMPARATIVE ANATOMY, Presenting a Sketch of the Present State of Knowledge, and of the Progress of Discovery in that Science; and designed to serve as an Introduction to Animal Physiology, and to the Principles of Classification in Zoology. By Robert E. Grant, M.D. F.R.S. L. & Ed. Professor of Comparative Anatomy in the University College, London. 8vo. Illustrated with 150 Woodcuts. London, 1835-41. 1 1. 8s. Part VII. just out, Is. 6d. ON THE PRINCIPLES ©F CLASSIFICATION, AS APPLIED TO THE PRIMARY DIVISIONS OF THE ANIMAL KINGDOM, By Robert E. Grant, M.D. F.R.S. L. & Ed. Professor of Comparative Anatomy in the University College, London. 12mo. Illustrated with 28 Woodcuts. London, 1838. 3s. 6d. In the British Annual, 1838. PROFESSOR GRANT'S GENERAL VIEW OF THE DISTRIBUTION OF EXTINCT ANIMALS. 18mo. London, 1839. 3s. 6d. In the British Annual, 1839. ON THE DISEASES AND DERANGEMENTS OF THE NERVOUS SYSTEM. By Marshal Hall, M.D. One vol. 8vo. illustrated with 8 Engraved Plates. London, 1841. Price 15s. ICONES OBSTETRSC/E, A Series of 60 Plates, illustrative of the Art and Science of Midwifery, in all its Branches. By A. L. Moreau, Professor of Midwifery to the Faculty of Medicine, Paris. Edited with Practical Remarks, by J. S. Streeter, M.R.C.S. Complete in 10 Parts, 60 Plates, with Descriptions, in cloth boards. London, 1842. Plain, 31. 3s. ; coloured, 61. 6s. THE ANATOMY OF THE NERVES OF THE UTERUS. By Robert Lee, M.D. F.R.S. Folio, with 2 Engraved Plates. 1841. 8s. ELEMENTS OF THE GENERAL AND MINUTE ANATOMY OF MAN AND THE MAMMALIA, CHIEFLY AFTER ORIGINAL RESEARCHES. BY FR. GERBER, PROSECTOR IN THE UNIVERSITY OF BERN. TO WHICH ARE ADDED, NOTES AND AN APPENDIX, COMPRISING RESEARCHES ON THE ANATOMY OF THE BLOOD, CHYLE, LYMPH, THYMOUS FLUID, TUBERCLE, &c. &c. BY GEORGE GULLIVER, F.R.S. Assistant Surgeon to the Royal Regiment of Horse Guards. TEXT AND APPENDIX. LONDON : HIPPOLYTE BAILLIERE, 219 REGENT STREET, FOREIGN BOOKSELLER TO THE ROYAL SOCIETY, AND TO THE ROYAL COLLEGE OF SURGEONS. PARIS: J. B. BAILLIERE, RUE DE L’ECOLE DE MEDECINE. LEiPSIG : T. O. WEIGEL. M.DCCC.XLII. PREFACE. General Anatomy, in connexion with that portion of physiological science which treats of the evolution of animals, has not only made signal pro- gress in recent times, hut in the interesting shape in which it now presents itself, has acquired new claims to our attention : more than this, it is found daily to gain in importance in its relations to natural science at large, and to scientific medicine in particular. General Anatomy, indeed, is now seen to form the indispensable basis not only of descriptive anatomy, hut of physiology and the science of evo- lution, and farther of morbid anatomy, and there- fore of pathology. The changes that take place in the constitution of our organs, and that give form and character to a large proportion of the more formidable diseases to which we are obnoxious, occur in the elementary and constituent atoms of these organs ; we can no longer sit down contented with such general affirmations of morbid states as VI PREFACE. satisfied our immediate predecessors, — indurated, softened, enlarged, altered in appearance, &c. &c. are expressions that cannot now he received ; we would he informed of the changes that have taken place in the intimate structure of parts, and that have led to the induration, the softening, the enlargement, the alteration in appearance, &c. The microscope, now recognised as indispens- able in general and pathological anatomy, ought also to take its place among the implements most needful to the practical physician. It seems im- possible, indeed, to over-estimate the extent to which the science and art of medicine would he advantaged were every well-informed and zealous practitioner carefully to examine each morbid pro- duct he encountered, and to communicate the results of his inquiries along with a compendious history of the case. FR. GERBER. Bern, 1840. TO THE READER. To Dr. Craigie belongs the merit of having written the first distinct and comprehensive English work on General Anatomy ; Mr. Grainger’s Treatise on the same subject appeared almost immediately afterwards, and the translation of Bedard’s book, by Dr. Knox, soon followed. All these works are valuable, and each has undoubt- edly been of essential service in advancing the knowledge of Minute Anatomy in this country. But the progress of this branch of science has of late years been so rapid that, to give a tolerably accurate account of its present state, an entirely new publication has become necessary. The work of Gerber has been commended by Rudolph Wagner, “ as the latest and best” on the subject of which it treats. That all we should like to see in such a treatise is accomplished, it would, I con- ceive, be vain to assert ; but the work appears to me to be generally highly interesting, and I believe that it cannot fail to prove serviceable to English anatomists. Vlll TO THE READER. Improvement in science, with a few brilliant excep- tions, is gradual ; it results from the united toil of many observers ; and if every careful and laborious effort be the means by which a step is gained, the present publication, like its predecessors, will certainly be useful. The sheets of the English version of Mr. Gerber’s work were submitted to me with the request that I would add some notes to the text. Hence the Appendix and the Notes marked “ G. G.,” which comprehend all that I have done on the occasion. The engravings illustrative of my observations are after drawings by Mr. Siddall, a zealous micrographer and the worthy veterinary surgeon of the Blues. I am also indebted to Dr. Boyd, the excellent resident physician of the St. Marylebone Infirmary, for his friendly assistance on various occasions. GEORGE GULLIVER. Windsor, November 1841. CONTENTS GENERAL ANATOMY. PAGE INTRODUCTION 1 ELEMENTARY CONSTITUENTS OF THE ANIMAL BODY 4 GENERAL ANIMAL CHEMISTRY: Review of the chemical constituents of the ANIMAL BODY ....... 5 Simple Chemical Constituents .... 9 Compound Chemical Constituents . . . .10 Of the interchanges and general transforma- tions OF ORGANIC MATTER .... 11 Formation of Solids from Fluids . . . .12 Of the forms in which the constituent elements OF ANIMAL BODIES PRESENT THEMSELVES . . 14 Of the Fluids ........ 15 Elastic Fluids, Gases ..... 15 Inelastic Fluids, Liquids ..... 16 Serous or Watery Fluids ..... 18 Oily Fluids, or Animal Oils . . . .19 Of the Solids ....... 20 I. Unorganised Solids ...... 20 II. Imperfectly organised Solids : Amorphous Solids — Hyaline or Vitreous Sub- stance ....... 27 III. More highly organised Solids . . . .28 Morphic Solids or Organic Elements : Fibrine ....... 28 Organic Granules ..... 37 X CONTENTS. IV. Completely organised Solids ; parts endowed with inherent life and capable of peculiar evolution : Cell-germs or Cytoblasts .... Cells Chyle and Lymph ..... Chyle ........ Lymph ....... Blood ........ Origin, evolution, and ultimate structure of the LIVING CONSTITUENT ELEMENTS OF ANIMAL BODIES, AND OF THE ANIMAL TISSUES .... Motions and Changes of Place of the Fluids Gravitation of Fluids ...... Hydrostatic or Passive Congestion . . . . Active Congestion ...... Normal escape of the fluids from the vessels: General Endosmotic Transudation . Morbid escape of fluids, particularly of the BLOOD FROM THE VESSELS: Extravasation ....... Exudation ........ Morbid Exudation in consequence of Inflammation Morbid Exudation of Blood (Hemorrhage) . Serous Exudation ...... Plastic Exudation ...... Exudation-corpuscles ..... Formation of pus: reproductive organisation in SUPPURATING WOUNDS . ... . Pus ......... False Pus ........ Fluid of Bullae, Phlyctenae ..... Fluid of Ulcers (Ichor) ...... Contents of Cysts, or Morbid closed Cavities Organisation of the exudation in suppurating WOUNDS (GRANULATION, CICATRIZATION) Granulation . . . . Cicatrization ........ PAGE 40 45 49 55 60 61 71 72 73 74 75 75 77 77 78 78 79 79 83 89 90 101 104 105 107 110 114 116 CONTENTS XI PAGE Of the primary organising process in the impreg- nated OVUM 116 The Foetal Ovum ....... 117 The Unimpregnated Ovum in the Adult . . 118 Origin of the Ovum . . . . . . 120 Earliest Period of Developement in the Fecundated Ovum, and Origin of the Embryo in the Incu- bated Egg ....... 121 Of the formation of the various compound parts AND TISSUES FROM CELLS .... 124 Of the Different Constitutions of Cells . . .127 Pigment, Pigmentary Cells ..... 131 Fat cells ........ 133 Horn cells and horny tissues .... 135 External Horny Indusise. — Epidermis, Epithelium, and Structures connected with them . . . 136 The Sebaceous Glands, the Sweat Glands . . 138 Sebaceous Glands ...... 138 Sudoriparous Glands ..... 143 Hair ......... 144 Tactile Hairs ....... 147 Wool . 148 Bristles ........ 148 Horny Defences ....... 148 Implanted, Flat Horny Structures : Nails ........ 149 Claws 151 Horny Capsules . ...... 151 Hoofs of the Hog ...... 153 Hoofs of the Horse ...... 153 Horns of the Ox, Sheep, &c. .... 155 Coverings of the Internal Surfaces of the Body — Epithelia ....... 156 Tessellate Epithelium ...... 157 of the Lymphatic and Sanguiferous Systems 158 of the Serous and Synovial Sacs . . 159 of Mucous Membranes .... 160 Xll CONTENTS. rAGE Ciliary Tessellate Epithelium . . . .161 Cylinder Epithelium ..... 162 Ciliary Cylinder Epithelium .... 163 Inversions of the Mucous Epithelia . . . 166 Epithelial Glands . . . . . .166 Mucous Crypts and Follicles ... 167 Mucous Glands ...... 167 Arrangements of the Glands in General . . 169 Cartilage : Permanent Cellular Cartilage .... 171 Ossific Cellular Cartilage ..... 174 Reticular Cartilage ...... 175 Fibrous or Fibro-cartilage 176 Osseous Cartilage 176 Normal Ossification of Cartilage .... 177 Ossification of the Costal Cartilages ... 178 Bone : Formation of Bone in the Foetus Ossific Points, Bone Nuclei . Microscopic Analysis of Bone . Chemical Analysis of Bone Elevations or Processes of Bone Depressions of Bone Articulations between Bones Teeth ........ Enamel, Vitreous Substance Proper Substance, Tubular Substance, or Ivory Bone, Cement, or Crusta Petrosa External Forms of Teeth and their Relations to the Jaws ........ Formation of the Teeth in the Foetus 185 185 186 188 190 191 192 194 194 197 199 201 203 Of the tissues 204 Elastic Tissue ; Intercellular Rete ... 204 Proper Fibrous Tissues ...... 210 Cellular Substance ...... 211 Investing Cellular Substance . . . .215 Entering into the Composition of other Tissues 215 CONTENTS. Xlll PAGF Fibres of Cellular Substance .... 216 Membranes of Cellular Substance . . . 216 Serous Membranes ...... 217 Synovial Membranes . . . . .217 Tendon — Tendinous Fibre 221 Tendinous Tissue ...... 223 Long Tendons, Sinews ...... 223 Tendinous Expansions ; Aponeuroses ; Fasciee . 224 Intermuscular Tendinous Septa .... 224 Tendinous Muscular Sheaths .... 225 Tendinous Membranes strengthening the Serous and Synovial Membranes ..... 226 Peculiar Fibrous Membranes ..... 226 Fibrous Bands ; Ligaments .... 227 Fibro- cartilage ....... 229 Contractile fibre ; contractile tissue . . 229 Muscle; Muscular Fibre ; Muscular Tissue . . 231 Organic or Involuntary Muscular Fibre . . 232 Passage of Organic into Animal Muscle . . 235 Animal or Voluntary Muscular Fibre . . 238 Origin and Evolution of the Animal Muscles in the Embryo ........ 243 Microscopic Examination of the Living Muscle of Animal Life ...... 246 Chemical Constituents of Muscle .... 248 Sensibility, &c. of Muscles .... 248 Tubular or hollow produced or filamentous tissues ........ 251 Nerves ; Nervous System ..... 252 Microscopic Analysis of Nerves .... 256 Peripheral Terminations of Nerves . . . 261 Organic or Ganglionic Nerves .... 264 Ganglionic Globules or Cells; Grey Nervous Sub- stance ; Ganglia . ..... 265 Origin and Evolution of Nerve in the Embryo . 267 Chemical Composition of Nervous Matter . . 269 CONTENTS. xiv Vessels ...... Absorbent Vessels .... Lacteals and their Glands Lymphatics and their Glands Blood-vessels — the Sanguiferous System The Heart ..... The Arteries ..... The Veins ..... Erectile Vessels and Erectile Organs ■ . Erectile Vessels .... Organs .... Of certain effects of the deranged action of THE CAPILLARY VESSELS, AS PROCLAIMED IN THE FORMATION OF TUBERCLE . . . . . Albuminous or Unorganised Tubercle Fibrinous Tubercle ...... Hyaline Tubercle ...... Cytoblast Tubercle ...... Cell and Cellulo-fibrous Tubercle Filamentous or Cicatricular Tubercle Origin of the Blood-vessels ..... Secreting Vessels and Apparatus . . . . Evolution of Mucous Cavities and Canals in the Em- bryo Evolution of Glands ...... Of the Skin and Mucous Membranes Valves of Excretory Vessels or Canals Division of Glands ...... Proper Secreting Glands . Simple Secreting Glands .... Mucous Follicles ...... Sebaceous Follicles ..... Compound Secreting Glands .... Aggregated Glands ..... Vesicular Glands ...... Lachrymal Glands and Fluid PAGE 270 272 272 280 284 287 287 294 298 298 300 302 305 306 306 306 307 308 309 313 314 316 318 322 323 324 325 326 327 328 328 328 329 CONTENTS. XV PAGE Salivary Glands and Fluid . . 330 Pancreas and Fluid 332 Liver and its Fluid . . 332 Mammary Gland and Fluid 332 Tubular Glands . . 333 The Kidney and its Fluid 333 The Testis and its Fluid . . 335 Organ, Apparatus, System 337 Literature of the general anatomy . . 339-390 APPENDIX BY G. GULLIVER, F.R.S. Observations on the blood-corpuscles of mam- MIFEROUS ANIMALS I, Size of the Corpuscles in General ... l in different Mammals ... 5 II. Form of the Corpuscles .... 9 III. Changes of Form of the Corpuscles . . .11 IV. Structure of the Corpuscles .... 12 V. Microscopic Corpuscles of the Blood unlike the Common Discs ....... 14 VI. Formation and Use of the Corpuscles . . 23 On the blood-corpuscles of birds . . .23 I. Size of the Corpuscles ..... 25 II. Form of the Corpuscles ..... 29 III. Structure of the Corpuscles .... 30 Tables of Measurements of the Blood-discs of Mammalia 31 Tables of Measurements of the Blood-discs of Birds . 55 Observations on Tubercle ...... 84 XVI CONTENTS. Observations on the Chyle, and on the Fluid of the Thymus, and of the Lymphatic Glands . I. Chyle II. Fluid of the Thymus, and of the Lymphatic Glands ....... On the Corpuscles of the Liver . On the Corpuscles of the Spleen .... On the Supra-renal Glands . PAGE 88 88 95 101 102 103 4 GENERAL ANATOMY. INTRODUCTION. Anatomy is that branch of natural science which treats of the structure of organic bodies, — which investigates the connexions, forms, external and internal relations, and intimate constitution of all that is organised. Anatomy is, therefore, a generic term, including the consideration of the structure of man — human anatomy, or anthropotomy ; of ani- mals COMPARATIVE ANATOMY, Or ZOOTOMY ; and of plants VEGETABLE ANATOMY, 01’ PHYTOTOMY. Anatomy is further necessarily distinguished, ac- cording as the healthy and natural structure is its object, normal anatomy ; or, as the diseased or abnormal structure engages attention, abnormal anatomy. Abnormal anatomy is itself subdivided according as changes wrought by disease in the organs, originally of healthy constitution, are the object of contemplation, when it is entitled morbid or pathological anatomy ; or, as original and congenital deficiencies, superfluities, or imperfec- tions are the subjects of study, when it is entitled B 2 INTRODUCTION. the ANATOMY OF ANOMALY, OT ANOMALOUS ANA- TOMY, PHILOSOPHICAL OF TRANSCENDENTAL ANA- TOMY. When anatomy is cultivated merely as a science, and in books, it is spoken of as theo- retical anatomy ; when researches are under- taken in the bodies of men, animals, &c. it is known as PRACTICAL ANATOMY, OT the art of DISSECTION. The art of dissection is systematically pursued when the various, especially similar, parts of the subject are exposed in their sequence or connexions. When the several parts, again, especially of dissimilar nature, which enter into the constitution of each particular district of the body are exhibited in their several situations, and in their mutual mechanical relations, the study acquires the name of sur- gical or regional anatomy. Finally, anatomy is divided into general and special. The busi- ness of the general anatomy is to take cogni- sance of the most simple and minute, or elementary parts of organic bodies, and of the union of these in the composition of particular organs , such as the brain, the lungs, the liver, &c., and of certain systems into which they are found susceptible of arrangement, such as the fibrous, the muscular, the glandular, the nervous, &c. General Anatomy, further, under the name of Histology, studies the texture and mode of formation of the different com- pound organs, and indicates the reasons for the diversities they present. Special or descriptive anatomy, again, considers the forms, situations, relations, connexions, and modes of distribution of the several organs or systems which make up the bodv. INTRODUCTION. 3 Anatomy, then, has the structure of organic beings for its object. But we do not limit our- selves to the study of the structure alone ; we have ever an eye to something beyond this — to the uses or functions, namely, of the organs we discover. A new science is therefore engrafted upon anatomy, — a science which treats of the functions of organised beings, and this is entitled Physiology. Like anatomy, physiology is sub- divided variously, and is appropriately designated according to the direction in which it is studied. We do not, however, speak of a morbid physiology as we do of a morbid anatomy, when we consider the functions of an organism in a state of disease. Pathology is the term which is here employed ; so that pathology is to he understood as having the same relation to physiology which morbid anatomy has to normal anatomy. Anatomy and physiology, however, ought never to be viewed as sciences altogether disjoined and different ; they are, indeed, so closely linked together, that they are all but one and the same : in anatomy, we study the organs in repose, in physiology, we study them in action. It is now universally allowed that an adequate knowledge of the structure and functions of the human body is the only foundation of all medical science. Without this essential preliminary, it is just as impossible to distinguish disease, and to treat it rationally, as it is for a tree without roots to put forth blossoms and to bring fruit to matu- rity. Nor are the researches of the anatomist and 4 ELEMENTARY CONSTITUENTS. physiologist confined in the present day to the structure and functions of the body of man alone. It is customary now to embrace all that has life, — to contemplate organisation in the linked chain which it forms, and to connect structures and func- tions of the first simplicity with structures and func- tions of the last complexity. It is, in fact, only since comparative anatomy and general physiology began to be seen as integral parts of a liberal pro- fessional education, that scientific, and then prac- tical, medicine and surgery have made any thing like vigorous or assured strides in advance. If we he made but a little lower than the angels, we are also very certainly made but a little higher than the more perfect among the animals ; and in studying the structure and functions of these especially, we find the most important aids to a right understand- ing of the mechanism by which we ourselves “ live, and move, and have our being,” and thence, under the guidance of reason and experience, of the means by which we may hope to ward off or to remedy the ills in the shape of infirmity and disease to which we are made obnoxious. OF THE DISSECTION AND ELEMENTARY CON- STITUENTS OF THE ANIMAL BODY. § 1. The object of the anatomist is to exhibit, in systematic arrangement, the organic constituents CHEMICAL CONSTITUENTS. 5 of the body, by investigating and separating the various organs of which it consists, indicating their similarities and their differences, discovering their mutual connexions, unravelling the tissues, laying the hidden open, and distinguishing the ultimate forms of organic matter with the aid of the mag- nifier and the microscope. The object of the chemist, again, is to separate mingled elements without paying any regard to their form, texture, or arrangement. § 2. The organic constituents of the animal body are, like chemical elements generally, divi- sible into proximate or compound, and remote or simple : for example, the blood corpuscules form a proximate or compound organic element of the blood, the outer coverings and the nuclei of these bodies a remote or simple organic element of the same fluid ; hydrogen and oxygen are simple, water and fibrine compound, chemical elements of the blood. GENERAL ANIMAL CHEMISTRY. REVIEW OF THE CHEMICAL CONSTITUENTS OF THE ANIMAL BODY. § 3. In inorganic bodies the chemical elements are always associated in twos, or they form binary combinations : for example, oxygen and iron, in cer- tain proportions, form oxide of iron ; oxygen and sulphur, in certain proportions, form sulphuric acid ; 6 CHEMICAL CONSTITUENTS. protoxide of iron and sulphuric acid form sulphate of the protoxide of iron, Oxygen T ( Protoxide of iron'i 0 , , , c Iron J | sulphate ot the Oxygen 1 c , , . ... | Protoxide of Iron. • & > Sulphuric Acid J Sulphur J This binary combination prevails universally throughout the entire domain of inorganic nature, and is essential to quiescence or chemical equi- poise : any other combination of chemical elements is incompatible with chemical quiescence, and is by so much the more vigorously opposed by surround- ing media and influences, — air, water, caloric, electricity, light, &c., in order to reduce them to binary combinations, the more the kind of combi- nation attempted is remote from the binary ; the vital force alone, assisted by ceaseless changes of matter, proves adequate to produce and to support for a limited period the ternary and quaternary compounds which we encounter in the bodies of living plants and animals. § 4. In consequence of the prevalence of ternary combinations in plants, Oxygen "i H d ’ o- l Vegetable compounds, Carboif011/ Vegetable matter, when they die they are obnoxious to decomposition ; under the requisite conditions (access of air, the presence of moisture, and a certain degree of tem- perature) their constituents immediately begin to fall into the binary combinations of the inorganic world. This resolution of the vegetable elements takes place by three different, but consequent pro- CHEMICAL CONSTITUENTS. 7 cesses of decomposition, — the vinous , the acetic , the putrefactive fermentations * § 5. The empire of the universal chemical laws is asserted in, if possible, a still more striking man- ner upon the matter of the dead animal body, with its elements made up of quaternary compounds, azote being added to the three principles already noted in vegetables. The two first forms of fermentation, if they be not entirely absent, are here so quickly accomplished, that, in general, they are not observed ; and the putrefactive fermentation, which is due to the pre- sence of the nitrogen, under favourable conditions, leads rapidly to the decomposition and change into binary compounds of all even the most solid of the highly animalised tissues. The reason of the slighter tendency to decomposition manifested by the less highly organised parts of the animal body, which are usually binary and ternary compounds, such as fat, the earthy portion of the hones (phos- phate and carbonate of lime), and the horny tissues (in which azote is almost wanting), is obvious from what has already been said (§ 3.). On the same * In the herbivorous animals we observe three correspond- ing and distinct digestive processes, — -ventricular digestion, with the vinous or, rather, a stage preliminary to this, the saccharine fermentation ; small intestinal digestion, with acid fermentation ; and great intestinal digestion, with more or less of the putre- factive fermentation. 8 CHEMICAL CONSTITUENTS. principles, it is easy to explain the more ready digestibility and more nutritive qualities of animal food, i. e. of quaternary organic compounds, than of articles taken from the vegetable kingdom, or ter- nary combinations. In the one case, a quaternary compound, viewing the animal body as an unit, is at work upon matter already akin to it ; in the second, it is dealing with ternary combinations, which must have a fourth element added to them, and so be raised in the scale of organic compounds, before they can he assimilated and made fit to become a part of itself. In direct contrast to the horny and bony structures, stand the brain and nervous centres, which, as the softest, at once, and most highly animalised of all the organic struc- tures, fall the most rapidly into putrefaction. With the chemical decompounding processes, especially as they affect the animal body, softening and liquefaction are generally associated ; in these respects, therefore, they stand in opposition to the formative powers of the organism, to the solidifica- tion of the elementary tissues out of fluids — out of the blood, for instance. Coagulation, as this so- lidification in its earliest stage is entitled, is ex- hibited in the formation of the crassamentum, as a kind of final manifestation of vitality by the blood ; with the commencement of the chemical decomposition which ensues, the coagulated blood is resolved, it again becomes a fluid. Even so in the living animal body do we observe the same opposed tendencies : predominating plasticity, or disposition to coagulation and induration along with an excess, and colliquation or a tendency CHEMICAL CONSTITUENTS. 9 towards resolution and liquefaction along with a lack, of vital power.* § 6. The inorganic or binary, as well as the organic, combinations which are encountered in animal bodies, and produced under the influence of the vital power, present themselves in a variety of forms : amorphous, as gases, vapours, liquids ; and with determinate forms, as solids. Simple Chemical Constituents. § 7- Of the universally diffused simple ele- mentary substances, the following have been found as constituents of animal bodies : — oxygen, hydro- gen, carbon, azote, phosphorus, sulphur, chlorine, fluorine, scilica, potash, soda, lime, magnesia, iron, manganese. The carbon, sulphur, azote, and phos- phorus, belong particularly to the organic kingdom of nature ; the two latter, to the animal division of it.t * In this consolidation of the plastic fibrine in the organic separation of the blood, and this resolution or liquefaction of the same element in its chemical decompositions, aided by the nor- mal transudations, or endosmoses and exosmoses, lie the true conditions to nutrition and reproduction in general, viz. the animalisation or change of fluid blood into solid organised ani- mal matter, and the cfoanimalisation and reliquefaction of the same matter, vanquished by the chemical affinities, to admit of its being resorbed and then removed from the economy. f Perhaps it would be more correct to say that the carbon and sulphur are encountered in like abundance in the inor- ganic and in the organic kingdoms ; that azote is an essential and most abundant ingredient of the atmosphere, as well as of most animal (fat, oil, spermaceti, cholesterine contain no azote) and many vegetable bodies ; and that phosphorus is principally known as an element of the organic kingdom, particularly of its animal subdivision. 10 CHEMICAL CONSTITUENTS. Compound Chemical Constituents. ( A ) Inorganic ( binary ) Combinations. § 8. Water, carbonic acid, hydrochloric acid, sulphate of potash, chloride of potassium, sulpo- cyanide of potassium, sulphate of soda, carbonate of soda, chloride of sodium, carbonate and bicar- bonate of ammonia, hydro-chlorate of ammonia, phosphate of lime, carbonate of lime, sulphate of lime, chloride of calcium, fluoride of calcium, car- bonate of magnesia, phosphate of magnesia, scilica, oxide of iron, phosphate of iron, oxide of manganese. ( B ) Simple Substances in particular Combination with Animal Matters. Sulphur, phosphorus, iron. ( C) Salts with Inorganic Bases and Organic or Animal Acids. § 9- Lactate of potash, lactate of soda, lactate of ammonia, lactate of lime, lactate of magnesia, urate of soda, urate of ammonia, urobenzoate of soda, cholate of soda, sebate of soda, margarate of soda. (Z>) Animal Combinations. (a) Quaternary. § 10. Fibrine, albumen, gelatine, mucus, ani- mal extractive soluble in alcohol (osmazome) ; animal extractive taken up by water (of flesh, of the tears, of saliva, of the crystalline lens, of the seminal fluid — spermatine) ; farther, urea, caseine, picromel, resin of the bile, lactic acid, uric acid, TRANSFORMATIONS OF ORGANIC MATTERS. 11 pigmentary matters — as of the blood, of the choroid coat of the eye, of the rete mucosum or epidermis, of the horny tissues, &c. ( b ) Ternary ( Azote being absent). Sugar of milk, acetic acid, horny substance, and fat, which is a mixture of stearine and elaine. OF THE INTERCHANGES AND GENERAL TRANSFORM- ATIONS OF ORGANIC MATTER. § 11. Three of the compound animal matters, — albumen, fibrin, and gelatin, in combination with water, play the most important parts in animal bodies ; although in a state of purity, they possess peculiar properties, and, during life, have undoubt- edly different, imports, they are still so closely allied, that under the influence of the vital force, the one is readily changed into the other.* Fibrin seems to stand in the middle between albumen and gelatin, and to form a kind of transition step from the one to the other ; it is consequently met with in the general or all-pervading fluids — the blood and the lymph — as a principal ingredient. As food, these three matters are also the most nutritious, and in the fluid state the most digestible. * So are they, it would appear, readily convertible out of the body by means of certain chemical agents. M. Denis (“Essai sur 1’ Application de la Chimie a l’Etude Physiologique du Sang de l’Homme,” 8vo. Paris, 1840) found that an arti- ficial albumen could readily be produced by digesting coagu- lated fibrine in dilute solutions of many of the neutral salts, especially the chloride of sodium and the carbonates of the alkalies. 12 FORMATION OF SOLIDS. § 12. Animal matters, in general, as also the various excretions of animal bodies, — the carbonic acid of the lungs and skin, the excrements, the urine, the mucus, &c. are appropriated by plants as nourishment, and in their systems undergo trans- formation into the various forms of vegetable mat- ter we encounter ; and plants, again, consumed by herbivorous animals, suffer transformation into new shapes, and become fitted to form constituent ele- ments of their bodies. Here they remain for a time ; but, decomposed at length, they are expelled, and again become a portion of the vegetable world ; or, before decomposition, they are seized upon as food by some carnivorous creature, — man, quad- ruped, or worm, and made to serve for its subsist- ence. Organic matter, therefore, is in a perpetual round, passing from plants to animals, from animals to plants, and ever assuming new and appropriate forms. Vegetable matter, by the higher assimilat- ing powers of animals, becomes animal matter, soon again to fall back and suffer degradation to the simpler shape of vegetable matter. Formation of Solids from Fluids. § 13. Out of the fluid comes the solid, the shapen ; all the parts of an animal body were once fluid, — they have all been formed from the blood ; and after death they will revert to the fluid state again. Organic matter, itself engendered and de- veloped under the influence of the vital force, forms with water a vivifying fluid of different kinds, either homogeneous and more or less consistent, or having numbers of extremely minute and regularly organ- FORMATION OF SOLIDS. 13 ised molecules mixed with it. This vivifying fluid has the faculty, according to the circumstances in which it is placed, of coagulating or solidifying in different ways. The organic matter that is the most highly endowed with vitality separates in a state more or less highly organised, appropriately fash- ioned and susceptible of life, ever in conformity with the vitality and character of that which is around it, and with or without the solid elementary par- ticles with which it is mingled ; it then gradually acquires distinct and individual forms, which always bear appropriate relationship to the structures amidst which the separation takes place.* In the same measure and degree as the plastic and living, but in itself, and as regards particular form, indifferent blastema (§31) is consolidated on the one hand, the medium of solution passes off or quits it on the other, until at length the organised matter and the water come to stand in mutual oppo- * To this rule there are some remarkable exceptions. Be- sides the cartilaginiform, osseous, or earthy deposits, which are found in the fibrous parts, as age advances, many injuries are permanently repaired by a tissue, differing essentially from the one injured; and, in the course of the reparative process, tem- porary deposits often take place quite distinct in character from the structures in which they are formed. Numerous examples of both kinds might be cited. Fractures of the cpstal cartilages are commonly reunited by osseous matter. In fractures of the bones, whether of man or of the lower animals, "If there be much displacement of the fragments, bony matter will be generally found deposited in the neighbouring soft parts, although this irregular deposit is not to be expected when the fragments have been properly adjusted, — a fact which may help to explain the discordant results obtained by different observers. According to my experience, when the broken portions of bone form an 14 FORMS OF CONSTITUENT ELEMENTS. sition. Such vital fluids, in reference to animal bodies, are the blood and the lymph, the most universally distributed of all the fluids. From these all the solid parts of the animal body have been produced, by these they are maintained. It seems, therefore, essential that these primary, genetic fluids be particularly studied if we would hope to under- stand the mode of formation from them of the various animal fluids and solids. OF THE FORMS IN WHICH THE CONSTITUENT ELE- MENTS OF ANIMAL BODIES PRESENT THEMSELVES. § 14. The human and animal body, and indeed organised bodies generally, consist of fluid and solid parts. The fluid constituents are divided into elastic, and inelastic or liquid ; the elastic fluids, again, are arranged into permanently elastic, or gases, and condensible fluids, or vapours. The solid constituents, in like manner, fall into two angle, there is quite a distinct centre of ossification commencing in the soft parts that lie between the sides of that angle. This new bone being a provision to meet the exigences of an irregular case, I have ventured to term the accidental callus. It is, in fact, a sepa- rate point of ossification set up opposite to the broken ends of the bone, but at a distance from them, so as to facilitate the form- ation of a support between the fragments exactly in the most advantageous situation. The accidental callus, though for some time quite unconnected with the old bone, soon becomes united to the regular callus, the formation of the latter commencing between the periosteum and bone at a distance from the fractured extremities. For a figure of the accidental callus, see Drawings from the Anatomical Museum at Fort Pitt, fas. 3. pi. 9. fig. 6. and a notice in the “ Edin. Med. and Surg. Journ.” No. 129. — G. G. FLUIDS. 15 grand divisions, according to their degree of con- sistency, and are spoken of as soft solids, or as hard solids ; they are, also, sometimes classed in accord- ance with the degree of their organisation, and the peculiar forms they present, into simply solid con- stituents and solid fashioned constituents. Of the Fluids. § 15. Elastic Fluids . In the healthy state gases are only met with in certain of the cavities and passages which are lined with a mucous mem- brane, in the windpipe and its subdivisions, and in the intestines. They always consist of different species mingled together, and, both as regards qua- lity and quantity, are subject to perpetual variations, those in the lungs changing periodically and regu- larly, those in the intestines varying more accident- ally and irregularly. The air of the atmosphere, which is taken into the lungs, ; consists, as is well known, of 79 parts of azotic gas, and of 21 parts of oxygen gas, with certain slight admixtures, par- ticularly carbonic acid gas, vapours, dust, &c. which, with the exception of the carbonic acid, may all be regarded as more or less accidental. The carbonic acid, on the contrary, appears to be an essential ingredient in the atmosphere, — to be as necessary to vegetable as oxygen is to animal life. The gases and vapours of the intestines of animals generally consist of atmospheric air, with variable admixtures of carbonic acid gas, sulphuretted hy- drogen gas, &c. Many of the fluids, and per- chance even of the solids, contain combined gases 16 FORMS OF CONSTITUENT ELEMENTS. in small quantity ; * the blood always contains a small proportion of combined air, consisting prin- cipally of carbonic acid gas. Watery vapours mingled with gases only occur in the respiratory passages and alimentary canal, and upon the outer surface of the body. Their quantity generally bears a direct relation to the quantity and temperature of the gases with which they are mingled ; still they vary considerably, and are always in smaller proportion under stronger than under weaker pressures ; the air of the bowels in flatulence or tympanites, for instance, contains less watery vapour than the air of the lungs in ordi- nary respiration. § 16. Liquids, Inelastic Fluids. These consti- * Dr. Davy made an interesting series of experiments with the view of ascertaining whether any gases could be obtained from various parts of the body. His general conclusion was, that the solids, excepting those — the lungs especially — which are designed to be its recipient, contain no air capable of being removed by the air-pump. M. Proust, M. Vogel, and Mr. Brande, have maintained, at different times, that carbonic acid is contained in the urine. From this fluid, however, in the state of health, Dr. Davy could obtain no air ; and his numerous trials, with many of the secretions, gave the same result, with the exception of a single instance, in which a few minute spherules were procured from synovia, giving the idea of adventitious air entangled in the viscid fluid during the manipulation. As the results were perfectly negative in all his other experiments with synovia, as well as in those in which he opened the sheaths of tendons and the joints, with the requisite precautions, the state- ment of Laennec, that a small quantity of air is not uncommon in the synovial capsules, must be considered as requiring con- firmation. — “Researches, Anatomical and Physiological,” vol. ii. pp. 214-236. — G. G. WATERY FLUIDS. Y 17 tute the humours or fluids of the body, properly so called, and both as regards the space they oc- cupy and their weight, they exist in vastly larger proportion than the solids. The animal body always loses something like three-fourths of its weight by drying.* The fluids of animal bodies are always heterogeneous in their constitution. Their colour, the degree of fluidity they possess, and their other physical qualities, are as various as their chemical composition. The fluids, pro- bably condensed in different degrees, form an essential element in all the solid parts of the body ; or, otherwise, they are contained in particular re- servoirs and vessels, through which they are car- ried in a circle to every part of the body for its growth and maintenance, and for the accomplish- ment of each and all of the important vital pro- cesses ; or in which they are stored up till wanted for some particular purpose ; or by which they are thrown out of the system as useless. Among the humours or fluids of the body tve distinguish, 1. Watery or serous fluids, in which variable quantities of organic and inorganic matters are held dissolved ; 2. Oily fluids, — animal oils ; and 3. Fluids of a mixed character, they being made up of the two former in different proportions. * The entire dried body of an old woman, probably of seventy years of age, 5 feet 3 inches in height, preserved in one of the London museums, weighs no more than seven pounds; it must have lost seven or eight tenths of its original weight by desiccation. Where there is the largest proportion of fat, the loss by drying is least; where there is little or no fat, as in the subject alluded to, there the loss is greatest. C 18 FORMS OF CONSTITUENT ELEMENTS. § 17. The Serous, or Watery Fluids, consist of water in which more or less of albumen and animal extractive, and various salts are dissolved. These fluids are diffused through the whole body ; they enter as constituents into every one of the tissues, to which, in the main, they give volume, cohesion, softness, elasticity, colour, to a certain extent, and moistness, of course. They form, moreover, a very principal part of the general circulating fluids, — of the lymph and the blood, as the liquor lymphae et sanguinis, the liquid element of the lymph and of the blood, and of all glandular secretions ; they exist farther, in the transudations of all the serous cavities, in the interspaces of the cellular tissue, in the intestinal canal as the gastric juice and fluid of the intestines, and, with a larger proportion than usual of albumen, in all synovial cavities, sheaths of tendons, bursae, &c., as synovia ; finally they occur in the cavities of certain among the organs of sense, as in the watery fluid of the anterior and posterior chambers, and of the vitreous humour of the eye, in the labyrinth of the ear, as the aqua labyrinthi, and, lastly, in the foetal envelopes, as the liquor amnii. The specific gravity of these serous fluids is always somewhat higher than that of distilled water, and varies, in proportion to the quantity of the solid matter held in solution, be- tween 1*01 and 1-08. The watery fluids secreted by the glands, like the general circulating fluid, usually contain minute organised particles mingled with them ; and, more than this, as in the sper- matic fluid of the male, occasionally independent living animalcules, as essential elements. OILY FLUIDS. 19 § 18. The 0 ill) Fluids, or Animal 0*7$, are gene- rally sluggishly fluent, and occur more isolatedly throughout the body. Their colour varies gene- rally from a clear yellow to a green or a brown ; occasionally they appear gray. Their degrees of transparency are very different ; their specific gravities are not less so, varying between 08, and 0*94. In point of chemical composition they contain almost no oxygen, and hut little azote. Their proxi- mate elements, which are often separable by simple mechanical means, are fluid elaine, and solid stear- ine ; the amount of the latter determines the degree of consistency possessed by fat. Oily fluid, or fat, is prepared and stored up for different ends : in the cellular tissue, where it is secreted by par- ticular glands, it probably remains for the gene- ral uses of the economy, under peculiar circum- tances ; poured out upon the skin in the shape of sebaceous matter, it gives suppleness and softness to the common integument ; shed upon the edges of the eyelids, and into the cavity of the external ear, it fulfils obvious and most useful purposes. Some- times, again, we observe oily particles mechanically suspended in the fluids, as in the chyle, in milk, and now and then in the serum of the blood itself ; or otherwise, we find it chemically combined with an alkali, as in the bile, or with one or other of the simple substances, sulphur, phosphorus, & c. § 19. A mixture of a watery fluid with fat, and other matters, forms the bile. § 20. Animal oil, mixed with watery fluid is found in chyle, in milk, in the yolk of the egg, in the blood, &c. 20 FORMS OF CONSTITUENT ELEMENTS. We shall by and by treat of the blood, the lymph, and the different fluids secreted by the glands, under particular and separate heads. Of the Solids. § 21. The solid parts of the animal body are of various forms and composition. The elements of the solids, or simple textures of which they con- sist, by reason of their minuteness are only to be distinctly seen with the aid of optical instru- ments,— the single and double microscope. The form of the elementary solids depends either on physical and chemical forces, and then it is more or less accidental with reference to the body ; or being highly organised, their form is then deter- mined by the plastic powers of life, and is in har- mony as well with the parts around them, as with the entire body of which they form constituents. I. UNORGANISED SOLID PARTS. Fig. 164-179- § 22. Drops. — Fig. 164-169- Fluids of dif- ferent kinds when mixed together and left at rest, when no chemical affinity influences them, arrange themselves according to their specific gra- vity into superimposed layers. Agitation effects in the one or other of these fluids (generally in that which is the specifically lighter and smaller in quantity), a mechanical separation into small portions, which, in virtue of the force of cohesion, collect into globular drops. These drops are readily distinguishable scattered through the INORGANIC PRECIPITATES. 21 surrounding fluid, when their refractive power differs, as it very generally does differ, from that of the fluid. Globules of air in water or oil, of oil in water, &c., are perceived in virtue of the different refractive powers which they severally pos- sess ; and are distinguished from organic corpus- cles suspended in fluids, such as granules, glob- ules, discs and vesicles, first, by the great diver- sity they present in point of size, and secondly, by their complete transparency. If the fluid with which bubbles or drops are mingled, have a little mucilage, albumen, sugar, or any thing that will give it consistency, dissolved in it, the drops then remain distinct for a longer or shorter space of time ; in the contrary case, should the suspending fluid be perfectly limpid, if left at rest, they speedily coalesce. In several of the animal fluids, other fluids are included in the form of drops — air in saliva, oil in milk {fig. 22) and in chyle (fig- 23). § 23. Solid Precipitates . Fig. 170-179 All animal fluids contain several substances in a state of solution, as well organic and inorganic salts, as free alkalies and acids, and certain peculiar organic compounds, which occasionally separate as precipi- tates ; at one time in virtue of purely chemical laws, at another, through the agency of others less known, of an organic or vital nature. Inorganic precipitates take place : — 1. In consequence of an absolute diminution in the quantity of the solvent medium (which is generally water), and this may he brought about by («) evaporation ; by (&) penetration of other neigh- 22 FORMS OF CONSTITUENT ELEMENTS. Louring less fluid parts (imbibition and infiltration) ; (c) by absorption through the lymphatics and veins ; or, (d) as a consequence of secretion, when the fluid separated contains a smaller quantity of matter dissolved than the fluid from which it was elabo- rated. 2. In consequence of Changes produced by Admixture, (a) as when in consequence of a change effected in the solvent by a new substance, it be- comes incapable of holding one of its old ingre- dients in solution ; (&) when under the same cir- cumstances a new product is formed which is in- soluble ; (c) and when the products of double elect- ive affinities, though not insoluble, require more fluid to dissolve them than is present ; in this case a portion of the least soluble necessarily separates in the solid form. § 24. Inorganic deposits occurring in the animal body frequently contain organic matters mingled with them : gall-stones contain cholesterine, urin- ary calculi and gouty concretions contain uric acid, mucus, &c. Organic matters occurring under such circumstances, however, never present any of the appropriate forms or particular characters of organ- isation ; on the contrary, they are either crys- talline, or have their forms impressed upon them by mechanical contact or attrition. They may be aptly divided according to their forms, into 1. crys- tals ; 2. rolled gravel ; 3. granular gravel ; and 4. accidentally fashioned larger concretions. § 25. Crystals ( fig . 170-176-) These are bounded by determinate planes, angles, and edges. Crystals are encountered by no means unfrequently CRYSTALS. 23 in the bodies of men and animals, but only very rarely as normal constituents ; crystals, however, do occur in the labyrinth of the ear. They are much more common in the fluids of the different secretions, as in the liquor amnii {fig. 30, B.) ; in the various forms of morbid fluid deposits especially, and occasionally also in the intimate tissues of parts, as in the plexus choroides of the lateral ventricles, the pineal gland, &c. {fig. 30, A.) The forms of crystals are often indifferently characterised, and then they pass by insensible de- grees into calculi or gravel ; this is the case as regards the sandy particles of the pineal gland and choroid plexus, and the crystals of stearine {fig. 31, D.) Crystals arise in the animal body under the same circumstances, and in obedience to the same laws, as they do out of it, viz,, by the gradual ab- straction of the conditions under which the crys- tallisable matter is rendered soluble, - or is held dissolved ; they are, in fact, always either salts, or compound bodies analogous to salts, never simple substances, acids, oxides, or bases. Lamelliform and foliaceous crystals are easily distinguishable from organised squamae and lamellae, in their total want of every indication of organic formation. § “26. Rolled Gravel {figs. 29 and 177*) I thus entitle those small, globular, hard, inorganic deposits which owe their form, like the gravel of the beds of rivers, to their motion and mutual attrition. The globular gravel voided from the bladder [and renal pelvis ?] by the solidungula and 24 FORMS OF CONSTITUENT ELEMENTS. man, and the rounded concretions so often met with in the gall-bladder, may serve as examples of this form of deposit. It may have been originally crystalline, or it may, and frequently does, contain a crystalline nucleus ; I have only encountered this rolled gravel in mucous cavities, and in the larger excretory ducts. Similar formations, which receive their shape from the minute cavities in which they are produced without rolling or rubbing, for ex- ample, the concretions from mucous crypts, do not belong to the present category, but might be de- scribed apart, under the title of concrete gravel. § 27. Granular Gravel, Grit, or Sand ( Jig . 178). This occurs in the shape of small, hard, irregularly rounded, inorganic masses, of a reddish, grayish, or whitish colour, which still hear traces of their original forms, as irregular or imperfect crystals, with the angles and edges worn away. This kind of grit is therefore intermediate to the smallest perfectly crystalline precipitates and rolled gravel. It is, in fact, frequently found mingled with entire crystals, and with masses that have undergone attrition, and had secondary deposits let fall upon them in every degree. Such grit, or granular deposit, besides being met with in the renal and subordinate system, where it occurs very frequently, is also occasionally seen as an abnormal product upon the surface of serous, more rarely upon that of synovial, membranes, as on the pia mater of the brain, on the pleura, peritoneum, omentum, and tunica vaginalis testis ; also in abnormal cavities, in cysts containing watery fluids, &c. In point of GRAVEL CALCUjLI. 2 5 chemical composition, this kind of gravel differs essentially, according to the situation in which it is deposited. § 28. Mulberry Gravel ( fig . 179) occurs in the shape of agglomerated masses of grit, or small rolled gravelly particles, and is very generally found associated with simple grit, and with rolled gravel ; this occurs in the renal pelvis of man and of the horse {fig. 29, B.) It is met with only in cavities lined with mucous membranes, and is either a morbid product of the multiloeular or racemiform mucous glands, from which it then derives its form, or it acquires its irregular acinular shape by deposition in some unknown way. The best spe- cimens of this mulberry-like, or agglomerated gravel, are probably met with in the biliary ducts and reservoir. § 29. Accidental, mechanically formed {not mi- croscopic) Concretions. Besides the microscopic con- cretions now described, other accidental inorganic deposits are occasionally met with in the animal body, and generally in cavities lined with a mucous membrane, which derive their forms from the sur- rounding structures with which they are in contact, or which repeat, on a larger scale, the forms that are encountered in the different kinds of gravel on a smaller scale. To this category belong, gall- stones, urinary calculi, intestinal calculi, salivary cal- culi, lachrymal calculi, &c. When these inorganic matters are produced within one of the smaller cavities of the body, and continue to grow there till they fill it, they at length come out more or less perfect moulds of the receptacles or canals 26 FORMS OF CONSTITUENT ELEMENTS. where they were engendered. In this way, urinary concretions are met with that are accurate casts of the pelvis of the kidney ; biliary calculi, that figure the shape of the gall-bladder precisely; dacryoliths, that have the form of the lachrymal canal and its two afferent ducts ; salivary calculi, that are long and cylindrical, and even branched like a mass of coral, from having penetrated into the excretory ducts of the gland which prepared the fluid whence they were precipitated. When several concretions are formed in any of the situations indicated, they then acquire polyhedral and irregular forms, with rounded angles and corners, in consequence of their mutual contact and attrition : such forms are particularly common in the concretions of the gall and urinary bladder. When they occur singly, they generally present the figure of flattened ellipsoids ; this is by much the most frequent form of urinary calculi. They are also commonly enough globular in form — the intestinal concretions of the horse, and other lower animals, are almost always round. The cause of the extremly regular form often presented by calculous concretions of the mulberry and other kinds, when this can neither be traced to the in- fluence of crystallisation, nor of mechanical attrition, is less known. Finally, we now and then meet with a concretion that might, with some propriety, be spoken of as a single large crystal ; this is es- pecially the case as regards some biliary calculi. The whole of the concretions which are found in mucous cavities, consist of the chemical con- stituents of the fluids by which they are sur- rounded ; but they also occasionally contain prin- VITREOUS SUBSTANCE. 27 ciples derived from the mucous membrane. The normal and constant concretions of the living body, are the crystals of the labyrinth of the ear, the granules of the pineal gland and choroid plexus, the globular gravel of the urine of the solidungula, and the crystals of the liquor amnii. All the other inorganic precipitates are to he viewed as the accidental products of abnormal or morbid conditions. II, IMPERFECTLY ORGANISED CONSTITUENT ELEMENTS. Amorphous Solid Constituents ; Organic uniting Media — the Hyaline or Vitreous Substance (fig. 57 a, 6l a, 65 a; also Jig. 273-24-9.) § 30. The hyaline or vitreous substance, forms a considerable constituent element in the animal body. Although amorphous in itself, it must still be associated with the organic parts, inasmuch as it is formed cotemporaneously with other more highly organised elements, as it stands in a certain relationship to these, and for its maintenance re- quires, like them, a perpetual interchange of sub- stance. The vitreous element is translucent in every degree to perfect transparency ; it is colour- less, or but slightly tinged ; generally it is of firm consistence, and highly elastic. It serves as a transparent medium for optical purposes, as in the crystalline lens of the eye ; as a protecting and sheathing medium, as in the Whartonian pulp of the umbilical cord ; or as an elastic bond of union, — .as an intercellular substance, for instance, in the 28 FORMS OF CONSTITUENT ELEMENTS. cell-including vitreous matter of cellular cartilage, in the cartilage of the bones, and in the canalicular or tubular structure of the teeth. III. MORE HIGHLY ORGANISED CONSTITUENTS. Morphic Organic Constituents ( Jig . 180-238). § 31. Fibrine. — The fibrine which is held dis- solved in the serum of the blood and of the lymph, may he regarded as the general formative element or blastema — that principle which, under the in- fluence of the primary and secondary organic pro- cesses, is fitted to assume all the shapes which we observe in the constituent parts of animal bodies. Fibrine left at rest, consolidates, under all cir- cumstances short of those which act by decompos- ing it, first, into a determinate hyaline substance, which in the greatly debilitated and in the dead body, and also out of the body when left to itself, falls into granules, or forms an aggregated granu- lar mass.* Plastic fibrine has, therefore, in its * The softening of fibrine in the living body constitutes a distinct elementary disease of much interest, as well from its frequency as from its connexion with the prevailing doctrines about suppuration. M. Gendrin instanced mere softened clots of fibrine as cases of suppuration — transformations of fibrine into pus — and this view has since been generally adopted and promulgated in this country. Yet M. Gendrin also maintained that suppuration was a metamorphosis of the blood corpuscles ; thus confounding, as Mr. Palmer remarks, two distinct and well- known constituents of the blood. Dr. Young had long previ- ously stated his opinion, that the globules in pus are the glo- bules of blood somewhat altered in suppuration. — Medical Literature, 8vo. Lond. 1813, p. 509. In an inquiry, which I undertook with a view of ascertaining FIBRINE. 29 morphic changes, two forms in common with other coagulating matters — viz. the form of a vitreous substance, and that of granules. In animal oils, we already observe the formation of the constitution of pus, and of some other fluids with which it may be confounded, it appeared, that the liquid or pulpy matter in the centre of fibrinous clots, was totally distinct from pus, and that the softening of fibrine had been improperly confounded with suppuration. Besides its proneness to putrefaction, softened fibrine differs in some other chemical properties from pus ; and the characteristic globules of the latter are either wanting in the former, or not in sufficient quantity to render the matter iden- tical with pus. The mass of the softened fibrine, in short, is made up of a very minutely granular substance, frequently with some very irregular flaky particles — the globules which it often, and indeed generally, contains forming but a small pro- portion to the other materials ; whereas, the globules of pus constitute the bulk of the particles visible by the microscope. — Vide “Transactions Roy. Med. Chir. Soc.” vol. xxii. Probably, no subject in physiology is of more importance than the nature of fibrine ; and its structure and varieties, and the changes to which it is liable, are of the highest interest to pathological science. It appears to me, that a precise inquiry in this department is still wanting ; and that when completed, it must afford some valuable results. I am, therefore, induced to add, very briefly, an account of a few observations which I have made on fibrinous clots, with the hope of directing attention to this interesting field of research. Of the fibrinous exudations so frequently resulting from in- flammation, the structure agrees with the description of the author ; to which, however, it should be added, that besides the transparent matrix and the globules, a most minutely granular matter pervades the mass. The globules resemble those of pus in size ; and are, in fact, identical with those float- ing in the contiguous sero-purulent matter. At an early stage, they seem very granular on the surface and loose in texture, as if the globule were composed by the mere approximation of 30 FORMS OF CONSTITUENT ELEMENTS. granules, on a loss of temperature. This, how- ever, cannot he regarded in any other light than as an imperfect process of crystallisation ; — the precipitated granules of stearine are imperfect numerous granules. At a more advanced period, the globules have a more dense or compact appearance. Fig. 243 repre- sents a portion of coagulated lymph, magnified about 380 dia- meters, from a case of traumatic inflammation of the peritoneum in the horse ; the globules are held together by a hyaline matrix, and very delicate granular particles pervade the mass. From the microscopic characters, therefore, the term concrete pus, by which the French pathologists designate the fibrinous clots found within inflamed serous sacs, would not seem less ap- plicable to this matter than the appellation of Hunter — coagu- lated lymph. But these exudations are more or less firm — com- pletely preserving their integrity, however agitated with water ; whereas, there is a very common variety, generally co-existent with the other, also concrete, but most readily miscible with water. The difference seems to be, that one is a congeries of globules kept together merely by a little serous moisture, while the other is a coagulum of lymph pervaded by similar globules ; that the latter is the medium for a higher organisation, of which, as far as we at present know, the former is not susceptible. The microscopic and chemical characters of the globules are nearly, if not quite, identical in both varieties ; that miscible with water, is most frequently found in dependent parts of the inflamed sac, in consequence, simply, of a subsidence of the globules which form the mass. The structure, then, of the fibrinous exudations, resulting from inflammation, is so far complex, that we find globules con- nected together by a transparent clot of lymph, which is most frequently pervaded by exceedingly minute granules. Indeed, the opacity and colour of the whitish false membrane is mainly due to the great number of globules and granules it includes. Although the appearance of an aggregated granular mass is common, yet that fibrine, left at rest, always consolidates, as men- tioned in the text, into a determinate hyaline or granular sub- FIBRINE. 31 crystals {fig. 31 Voth of an inch in diameter. The compound corpuscle thus formed is generally round or oval, and about ^-J-(r5th of an inch in diameter. The corpuscles previously described may be sometimes found together in great abundance in one part of a clot, when the most diligent search is unable to detect them in another part not many lines removed ; and many clots may be examined without finding any of the corpuscles. Mr. Siddall and I found them in some fibrine, obtained by whipping, from the blood of a pregnant woman, but we could not detect them in the same fibrine two days subsequently. It may be suggested, that the corpuscles are the blood disks, entangled in the fibrine, although none of the colouring matter be visible. If so, the disks must have undergone remarkable alterations in size and figure, as well as in chemical properties. But this question comprehends a variety of considerations, which it is unnecessary to discuss here. — See Dr. Barry’s observations, “ Phil. Trans.” Part II. 1840. It may not be improper to remark, that the terms granules and granular seem to be employed in the text to denote an assemblage of most minute molecules, and that they are used in the foregoing note in the same sense. Granules are generally smaller than X2 o'oTyth of an inch in diameter, and in other re- spects utterly different from the corpuscles which have just been described. These latter are analogous in size, shape, and structure, to the primary cells of Schwann and Henle, and to the nucleated nuclei of Valentin, and appear to be the same as the fibrinous globules of M. Mandl, which he describes as form- ing, by coagulation, on the object-glass of the microscope. He says, that the fibrine of the frog, when separated by filtration from the blood-disks, is full of these white fibrinous globules, — a statement, however, at variance with the observation of Muller, that this fibrine is without corpuscles, and quite homo- FIBR1NE. 35 cles, which either swim free in the fluid, as the globules do in the blood ; or they appear as isolated bodies disseminated through a hyaline substance, or variously arranged without any common bond of union, and so attain their final developement ; or they present themselves as mere transition forms of more highly organised products, which, with the final completion of the developement, disappear en- tirely, These corpuscles are, in fact, the primary types of all higher formations in vegetable as well as in animal bodies ; they are, as it were, the universal organised condensations of the living- plastic fluids. The vegetable corpuscles have been named by Brown areolae, and by Schleiden, cytoblasts (cell-germs). There can be no ob- jection to the extension of these titles to the nu- cleolated nuclei of the animal kingdom ; and I shall constantly speak of these nucleolated nuclei under the name of cell-germs or encased nucleoli. § 32. In animal bodies, two classes of solid pre- cipitates from vital fluids may be distinguished, each of which has a different organic signification : geneous (“ Physiology,” by Dr. Baly, second eel. Part I. p. 124). Though M. Mandl saw “ perfect purulent globules ” in some delicate fibrinous shreds, separated by rods from blood diluted with white-of-egg, he found clots of pure fibrine, too compact to be examined successfully with the microscope. He considers the white globules of the blood, the globules of pus, of mucus, and those of the secretions, as identical. — “ Anatomie Micro- scopique,” Liv. i. et ii. I was unacquaintad with M. Mandl’s ingenious observations till some time after the foregoing note was printed. It will be seen, that my results having been obtained by the examination of compact masses of fibrine, either with or without tire assist- ance of chemical agents, were arrived at by a different method 36 FORMS OF CONSTITUENT ELEMENTS. Some are Objective, i. e. they form no immediate in- tegral part, essential to the life of the organisation ; and others are Subjective, i. e. they form immediate, original, and indispensably necessary parts of the body ; in other words, we have aplastic elements — elements susceptible of no farther amount of organisation, and plastic elements — elements which bear within them the germs of higher forms. Each of these classes of elements forms two orders ; the objective or aplastic fall into, 1. inorganic crystalline, and, 2. semiorganic, noncrystalline, mechanically fashioned. The inherently vital cell- germs again divide themselves into (a) monoplastic, which retain their primary forms and, ( b ) poly- plastic, which lose their primary shapes, trans- form themselves into all the organic forms, and, in fact, are destined to one that is higher. The opposite table is intended to convey an idea of these various relations, and at the same time to afford a compendious survey of the organization and evolution of the elements of animal bodies out of the cell-germ or encased nucleolus. See Table. from that pursued by M. Mandl ; and while he rejects the idea of nuclei, I have often seen them in great numbers, without any envelopes, as in fig. 250 ; and, indeed, that I am led to regard the corpuscles as organic germs, or primary cells, almost always with the characteristic nuclei, although these seemed to be ab- sent in some instances, as in fig. 249. The conclusion of M. Mandl, that the fibrinous globules are simply the result of coa- gulation, is not supported by the fact, that white globules, pre- cisely similar to those in the blood of the frog, may be seen circulating in the veins of the animal, moving very slowly along the inner tunic of the vessel, and often dropping into the central current of blood-disks, and liquor sanguinis, and then passing with velocity onwards. PRECIPITATES FROM the fluids in the living human and animal body, and development of those that are organised. r~ nr^cviti si Organisation. Formations capable op independent Organisation and paiitiier Evolution. Formations unsusceptible op indlpendi.nt partly Organised, but always incapable of Unorganised. further Dcvelopcnicnt. Organised, capable of peculiar Organisation. MIXTURES OF ORGANIC WITH INORGANIC MATTERS. ALBUMEN. FI BRINE . (Vitalised Albumen.) [To fat* paft SB. CRYSTALS. Chemical Forms : concretions. Mechanical Forms : coagulum. Organic Forms . CYTOBLAST, CELL OR onOANIC-OKKM, CASED Oil XUCLEOLATED NUCLEUS. Organic Forms: Enduring Cell-germs. Degenerating Partly Degenerating, portly Progressive , % Celt-germs. Cell-genu*. Lymph Blood Corpuscle. Corpuscle. Ichor Corpuscle. Exudation Corpuscle. Retrograding: Advancing in Dcvelopcnicnt: Pus Corpuscle*. cells. Retrograding and Vanish- ing Cell*, but leaving behind them Organised Cellular Substance. Permanent Cells. Progressive Cell*. Filamentous Hollow Isolated. Intercellular Intercellular Vitreous Substances. Substance. Substance. , ~ \ Cartilage Bone Cells. Cells. 5 2? o ~ •I % f a I Aggregated. Arranged in Rows. Ganglion Cells. Cellular Indusice : Epidermis, Epithelium . N'on-ciliate. Ciliale. Teacllatc Ciliale Epithelium. Epithelium. Cellular Fibres. Ovuin. C5C5 ' g B Enduring. j? | Non-ciliary. Ciliary. Z n 5-3F5- §. = “■3 S-wJ ?1 1 Becoming changed into fibres. Flat Fibres. ? Hollow Fibres. Round Fibres. Cellular Fibres. Tendinous Ligamentous Cartilage Fibre. Fibre. ' 'o-' o' Contractile Muscular Fibre. Fibre. GRANULES. 37 § 33. Organic Granules ; granular Coagulum. The precipitate of extremely minute, soft, organic granules, so universally encountered in the animal body, appears for the most part to consist of albu- men. These granules would seem only to form cell- germs, or nucleolated nuclei, when the coagulation of the fibrine takes place otherwise than in vital association with the internal structures of the indi- vidual who engenders it. There is scarcely a watery or mixed animal fluid without its granules : wherever albumen in solution is met with, there will granules be discovered. These granules, how- ever, are not always easy to be perceived : bright illumination and sharp definition, without which microscopical researches into the nature of transpa- rent elementary parts particularly, are of little value, are here indispensable. In the chyle, so long as it is contained in vessels beyond the mesenteric glands, granules only, from the th to the ^-i-g-th of a line in diameter, and oily globules,* are discovered ; but after the fluid has passed through these glands, and has reached the central vessel of the lymphatic system, it begins, in addition to these, to contain cell-germs (lymph-corpuscles). Aggregated mucus- globules (Jig. 25) (not epithelial cells), occur with- out admixture of cell-germs, because the secretion is too poor in fibrine ; on the contrary, in all transudations of the liquor sanguinis upon internal surfaces, or into the tissues themselves, encased nucleoli (exudation-globules), are produced. Wher- * These are generally from four to fifteen times larger than the granules. 38 FORMS OF CONSTITUENT ELEMENTS. ever the cell-germs perish, we also remark a retro- grade tendency to the formation of granules : from the exudation globule, we have the granular pus- globule, which, in its turn, and very speedily, may fall into its elementary granules. The embryonic cells, and the last formed epithelial cells, which are in immediate contact with the corium, are almost completely transparent, without any trace of granulation ; those that are cast loose, however, those of the lining membrane of the mouth, for example, are always granulated. § 34. Caseine, which bears so close an affinity to albumen, comports itself precisely like this sub- stance ; and, under the circumstances specified, like fibrine. The granular coagulum of diseased milk (fig. 23), cannot be confounded with the oil- globules of the fresh and healthy fluid (fig. 22). § 35. Granules are frequently seen collected into heaps or masses — aggregation corpuscles* (fig. 490) — of different sizes, and either globular, ovoidal, or ellipsoidal in figure. The elementary granules are here held together by a fluid, and se- parate when this is attenuated in any way, as by the addition of water, in which the corpuscles dissolve without leaving nuclei behind them. They are produced in small cavities — the mucus-corpus- cles (fig. 25, B) of the mucous crypts, t for instance, * I entitle all compound, rounded, isolated particles — glo- bules, ellipsoids, discs, lamellae, &c. — which enclose a nucleus, and consist of aggregated granules, corpuscles ; and when the nuclei include others (nucleoli), I call them cells. t Let a little piece of mucous membrane be washed with distilled water, by means of a soft hair pencil, all pressure being GRANULES. 39 or in unknown ways — the granular corpuscles, for example, which are often to be perceived with the naked eye in cysts with serous contents, and the granular pigmentary corpuscles {fig- 32, 1, a) of the pigmentum nigrum. § 36. When granules unite in rows like strings of beads, we have granular fibres* {fig- 189) pro- duced : several granular fibres lying in parallel apposition, form a granular fibrous cord, when this on a section appears cylindrical ; when it is not cylindrical, but flat in different degrees, it forms a granular fibrous bundle or fasciculus {fig- 191). When the fibres run in two directions, extending at the same time in breadth, they form a granular membrane {fig- 192). § 37. The number of granules present never hears any kind of ratio to the quantity of albu- men in solution ; so that a fluid which contains albumen in the proportion of fourteen, may present no more granules than one which contains albumen in no higher a proportion than one. The nucleus of a cell-germ, the nucleolus of a nucleated cell, often exhibits the precise appearance of a granule, avoided ; let the surface be gently dried by means of a clean napkin; now fold the piece of membrane with the mucous sur- face outwards, and press it gently between the finger and thumb near and towards the folded edge. A little pure mucus will exude ; and this being transferred to the stage of the microscope, between two fine plates of glass, the mucus-corpuscles will be seen in their highest perfection. * I designate as fibres all elongated formations, the sections of which, within short distances, present differences in form or size: other linear formations I incline to call filaments; and these are divided into cylindrical, flat, prismatic, and hollow. 40 FORMS OF CONSTITUENT ELEMENTS. but it can never be confounded with this, nor ought it ever to be spoken of as synonymous with a forma- tion of so much lower significance. IV COMPLETELY ORGANIZED CONSTITUENT ELE- MENTS PARTS ENDOWED WITH INHERENT LIFE AND CAPABLE OF PECULIAR EVOLUTION. § 38. Cell-germ , encased Nucleus ( Cytoblast Schleiden ). This formation had long been known as an essential and general constituent in the structure of vegetables ; but Schleiden* was the first (1838) who pointed out its significance in general, and espe- cially in reference to the process of developement in vegetables ; Valentin t and Schwann t subsequently (1839) shewed its identity, both in structure and office, with the cell-germ of animals. § 39. The cell-germ of the animal organism accords so closely with that of the vegetable, that Schleiden’s description of the latter might be applied in almost every particular to the former. § 40. The cell-germ of animals is, in the be- ginning, a globular, and by and by, a lenticular, or cake-like corpuscle, of a yellowish white or dull red colour, which encloses a nucleus, and is per- * Beitrage zur Phytogenesis (Researches on the Formation of Vegetables), in Muller’s Archiv. 1838, S. 137. t Entwickelungsgeschichte ; vide “Elements of Physiology” of R. Wagner, trails, by R. Willis, p. 214. t Mikroscopische Untersuchungen, &c. (Microscopical In- quiries into the Similarity in the Structure and Mode of Growth of Animals and Vegetables). Berlin, 1839. THE CELL-GERM. 41 petually produced in the shape of an organic pre- cipitate in the fibrinous vital fluids — the blood and the lymph. The dimensions of the cell-germ are different in different mammals, and under dif- ferent circumstances in the same mammal (from the Tg_th to the th of a line in diameter), and it bears a general relation to the size of the blood globules of the individual ;* its specific gravity is always greater the older it is, and this only de- * If so, it would be a remarkable fact in favour of the views of Dr. Barry, that the blood disks are transformed into cells. (“Phil. Trans.” Part II. 1840.) Schwann regards the red par- ticles of the blood, the lymph globules, and the globules of pus and mucus, as isolated cells. (“ Muller’s Physiology ” by Dr. Baly. Part I., second edition, page 399.) In a series of ob- servations which I made on the pus of various mammiferous animals, there did not appear to be any general relation between the size of the pus and that of the blood corpuscle of the same animal ; and in the Vicugna and Paco, which have oval red particles, the pus globules presented no peculiarity, being in form and size like those of many other animals. (“On the Blood Corpuscles and Pus Globules of certain Animals.” — Trans. Roy. Med. Chir. Soc., vol. xxiii.) Having discovered that the blood disks of the Napu musk- deer ( Moschus Jcivanicus, Pallas') were much smaller than any previously described in the vertebrate animals, I examined the lymph globules of this little ruminant, and found them of about the same size as in the human subject. In the blood of the Napu musk deer, many of the large white globules were ob- served scarcely differing from those found in other mammalia, thus forming a striking contrast to the singularly minute blood corpuscles. Nuclei were often seen in the white globules. In the blood of reptiles and birds, these globules are common ; but they are much of the same form and size as in mammiferous animals, notwithstanding the great differences between the blood 42 FORMS OF CONSTITUENT ELEMENTS. dines when it is again dissolved.* When the cell-germ is observed, whilst lying flat or on its side, its outline appears now round, and again elliptical ; and when many cell-germs are produced, and they corpuscles. Mr. Lane’s observations are to the same effect. (“ Lancet,” 1840, p. 121.) I find that the mucus-globules ob- tained from the mouth of a frog do not exceed in size those from the same part in the human subject ; and this observation applies to the cells of the epithelium, which were examined at the same time. — G. G. * The determination of the specific gravity of the micro- scopic constituents of animal bodies is important, both as re- gards the chemical and the organic analysis of these, inasmuch as it might frequently serve as a means of distinction between them : but it is at all times difficult to come to conclusions ; and when we have to deal with very small quantities, such as a grain or less, which constantly happens, conclusions seem alto- gether impossible. On this account, and as microscopic re- searches upon the animal body, combined with the use of water and various reagents, presume an acquaintance with microscopic endosmose, I shall take occasion in this place to describe my own method of proceeding to ascertain the specific gravity of the minutest animal constituents, and connect this with an attempt to expose the laws of endosmose, as they have de- veloped themselves in the course of my inquiries. 1. Every body weighed in water loses, as is well known, so much of its absolute weight (its weight in air) as the water weighs which it displaces. The specific gravity of the body is the quotient obtained when the absolute weight of the body is divided by that of the water which, in its immersion, it displaced. 2. The absolute weight of two bodies being a, the spe- cific gravities of the same bodies, a', c/1 ; and the weight of the masses of water which they respectively displace, b, /3 ; then we have for the first body, a'= consequently, & = ; and for the second body, a — a, is 5 consequently, The first body THE CELL-GERM. 43 lie crowded together, it may appear polyhedral. The cell-germ either fulfils the ends for which it exists, in the state in which it has now been described, or there is a vesicle developed upon and loses in water, b = -,: the second body loses in water, /3 == -(. a cl The weight a + a of the two bodies, when they are mixed and weighed in water, loses as under, — O' a ao! + a! cl a cl a! a! [= The specific gravity of the two bodies mingled, is, therefore, x. a + a a a! ( a + a. ) ^ na + a a, act + a! a. cl a 3. Suppose we have to determine the specific gravity of a minute quantity of a mixture of common salt and water : — Let the weight of the water be = 37 ; its specific gravity = 1. Let the weight of the dissolved salt be = 3 ; its specific gravity = 2T2 ; from what precedes, we have the following formula and result : — (1 X 2-12) X (37 + 3) _ 2-12x40 _ 84450 1-0113 x ~ (37 x 2-12) + (1 X 3) 78 44 + 3 8L44 4. Every body thrown into a fluid which remains under its surface, neither sinking to the bottom nor rising to the top, is of like specific gravity with the fluid. 5. Is the fluid sluggishly fluent and mucilaginous, from the admixture of mucilage, albumen, &c., then will very minute bodies, though specifically heavier than it, continue for a long time suspended in it, and only sink through it very slowly, as the blood-globules do in the liquor sanguinis, the albuminous granules in the serous fluids, the gallate of iron (a fine black powder) in the mucilaginous menstruum of ink, &c. &c. 6. In fluids which contain inorganic matters diffused through them, those that are insoluble soon sink to the bottom, remain suspended, or rise to the top, according as their specific gravity is greater, the same as, or less than, that of the fluid. When 44 FORMS OF CONSTITUENT ELEMENTS. around it which is called a cell. In the chyle and in the blood it floats at liberty, suspended in the peculiar liquors of these fluids, from which it is engendered ; it is, however, commonly met with they remain suspended, their absolute gravity is equal to the portion of the fluid which they displace. (4) 7. Upon these facts reposes my mode of determining the specific gravity of minute organic elements, as well as of inor- ganic matters, when they are only to be had in very minute quantity or in the form of fine powder, and when their specific gravity lies (as it all but uniformly does) between that of dis- tilled water and that of a concentrated solution of common salt. 8. It is essential to make use of a fluid in which the organic mattei’s to be weighed specifically are insoluble, and by which they are not altered, either in their chemical composition or in their density. 9. Organic animal matters in the recent state, without any exception, contain water as an integral constituent, and undergo changes in the ratio of the water they contain, by endosmose and exosmose (22), according to the following laws, which are inseparably connected with those of their specific gravities. 10. Organic matters are, in a high degree, hygroscopic, i. e. they soon come into equipoise, in point of free watery contents, with surrounding media. 11. This equipoise takes place when bodies and surrounding media have divided the free water between them, in the ratio of their powers of attraction for water severally. 12. Do the watery contents of surrounding media diminish, the organised matter takes up a certain proportion of these. Do the watery contents of media increase, the organic matters lose water to them ; and it is in virtue of this principle, that hygro- meters, or measurers of the moistness of the atmosphere, are usually constructed. 13. Organic and inorganic watery fluids, when they come into immediate contact, mix with greater or less rapidity accord- ing to the laws of affinity, with or without the formation of pre- CELLS. 45 also as a principal ingredient of consistent exuda- tions, &c. § 41. Cells. Cells arise from, or are developed upon, the living cell-germ ; upon one of the sur- cipitates, as the new combinations resulting from the mixture are insoluble or soluble. 14. The mutual attractions of gaseous or watery, of vaporous or fluid substances, are restrained or hindered in a greater or less degree, but never destroyed by the interposition of organic substances between them. Water included in perfectly close bladders, &c., evaporates through their parietes nearly with the same rapidity as if it were exposed under similar circumstances with the like extent of sur- face to the open air. The bladder is constantly taking up as much water from within as it is losing by evaporation from without. 15. The direction of the motion through an organised sub- stance, say, an animal membrane, is determined by the position and the predominance of one or other of the effective forces, viz. the chemical attraction or affinity, or the physical weight, pressure, &c. 16. When two precisely similar fluids, or two portions of a precisely similar fluid, such as distilled water, serum, syrup, &c., are separated in a vessel, by an animal membrane, be they placed side by side or lying one over the other, they remain at rest so long as the hydrostatic states are the same in reference to each, when, for instance, they are at the same level, standing side by side, when the pressure on the surface of each is the same, &c. 17. The hydrostatic equality being disturbed in ever so slight a degree, — the one being raised above the level of the other, the pressure on the superficies of the one being greater than on that of the other — then by degrees so much of the fluid will pass through the membrane from the higher column to the lower, or from that on which the pressure is more, to that on which the pressure is less, as is necessary to restore the hydro- static equipoise. 18. If the substances be different, and a chemical affinity 46 FORMS OF CONSTITUENT ELEMENTS. faces of this, a vesicle arises in the guise of a transparent hemisphere, which, in the beginning, is connected with the cell-germ, as Schleiden has subsist between them, then the following effects, independently of the physical relations, ensue : 19. When both matters are fluid, they will gradually come to equiponderate in point of their watery contents, through the permeable membrane — the one losing or giving water to the other, in the same proportion as the one has more or has less water than the other ; in this way, the degree of concentration of each portion of fluid finally becomes the same. 20. But in consequence of this transference of fluid from the one to the other, the hydrostatic equipoise, it may be presumed, will be apt to be disturbed, and so it is ; hydrostatic equipoise only becomes possible when chemical similarity is effected ; this accomplished, the physical law comes into operation, hydrostatic equipose is restored, and all subsides into quiet. (16) 21. The same thing follows when the animal membrane separates a menstruum from a substance which is solid but soluble in it ; for example, when water and common salt or 'sugar, are placed in opposition. Example. — A bladder filled with dry kitchen salt, and well secured, placed in a vessel of water, is penetrated by the fluid with such force that it is finally burst, if it be not all the stronger, or means are not taken to prevent the rupture. This fact led me to the following experiment, instituted with a view to measure the power produced in this way. Into the outlet of a glass funnel I luted, by means of sealing-wax, a glass tube thirty-one inches long; I then filled the funnel with dry, crystallised kitchen salt, closed the mouth of the funnel by stretching and tying firmly over it a piece of the dried small in- testine of the horse, softened in water immediately before the application. This apparatus I then plunged, the mouth downwards, the glass tube up- CELLS. 4>7 well observed, in the same way as the glass is connected with the watch. The formed cell is so much flattened subsequently, that the smaller cell- wards, the edges of the funnel resting upon three pieces of flint, into a shallow vessel of distilled water. In the course of a few hours the salt became moist, and long before it was all dissolved (therefore with the greatest degree of concentration of the saline solution), in between thirty and forty hours the solu- tion rose in the tube, and flowed over; I then rubbed the upper part of the tube with grease, in order to collect the drops as they escaped, of which, for some considerable time, two fell regularly in the course of a minute ; the height of the column of brine in the funnel and tube measured thirty-four Parisian inches. Although in this experiment the end proposed — the determination of the endosmotic force — was not attained, owing to the want of sufficient length in the tube, still the result was striking ; for, — The specific gravity of dry crystalline kitchen salt being 2T2, and the substance being soluble in 2-La, 0r 2-7647 parts of water, the specific gravity of the saturated solution must be 1-1632. Now, if a column of mercury, of about thirty English inches, presses with a force equal to fifteen pounds upon every square inch, and the specific gravity of mercury is 13-568, then will a column of pure water, of about thirty-four English feet, hold the column of mercury of thirty inches in equipoise, and a column of water, of thirty-four inches in height, press with a weight of 1-342 lb. upon the square inch, and a column of saturated brine, of the same height with a weight of 1-561 lb. The diameter of the base of the conical funnel is 32 lines, the basal surface formed by the membrane consequently is 5-266 square inches. The pressure of a column of saturated solution of salt upon the whole surface of the bladder will therefore amount to 8-22 lbs. Despite this resistance, then, the water attracted by the salt penetrated the membrane from without, in such quan- tity, that, for a length of time, two drops of the concentrated solution flowed over in the space of every minute. Second Experiment. — The funnel was filled with a satu- rated solution of salt, closed in the same way as in the first 48 FORMS OF CONSTITUENT ELEMENTS. germ occupies its middle as a nucleus, or there is a nucleolus evolved within a nucleus. The cell, like the simple cell-germ, either remains as such, or it is a mere transition form into other more highly organized products. experiment, and placed, as before, in distilled water. The solution stood 1 ft. 5 in. 7 lines above the surface of the water at first. The column in the course of the first minute after the immersion sank 22 lines, in consequence of the relax- ation of the animal membrane induced by contact with the water; but, in nine minutes, the column had regained its for- mer elevation ; and, with the lapse of seventy-eight minutes, the solution began flowing over. Third Experiment , Fig. 2. Over a common barometer tube filled with mercury, a glass funnel was passed, as in the accompanying figure, the space between the neck of the funnel and the tube being made air-tight with sealing- wax, the funnel itself filled with moist- ened kitchen salt, and its mouth covered with a layer of membrane as before, the apparatus was plunged in a shallow vessel of distilled water, and the upper closed end of the tube broken off so as to allow the mercury to sink and fill the reservoir. In the course of the first ten hours the mercury rose 101 lines; and, in the course of the second ten hours, 97 lines; twenty-four hours after the commencement of the experiment, the height of the column was 243 lines; and a column of mercury of this length indicates a pressure equal to 10-8 lbs. upon every square inch of surface. In the experiment just related the following corrections must be made : — a. By the rise of the mercury in the tube, it sank three lines in the reservoir. h. On testing the capillary force of the barometer tube, a CHYLE — LYMPH. 49 § 42. Chyle; lymph. The food — meat and drink — that is taken into the stomach, mingled with the peptic juices — the saliva, the gastric, and intes- tinal secretions, the bile and pancreatic fluid — and exposed to the nervous influence, heat, and pro- depression of the mercury equal to four lines was indicated (by so much did it stand under the level of the mercury in the reservoir) ; c. The saline solution in the funnel stood twenty lines above the mercury: a height of column that presses with 0-076 of a pound, and holds 1-47 line of mercury in counterpoise; the actual (effective) height of the column of mercury was thus 243+4 + 3 — 1-47=248-53, and the pressure upon each square inch of membrane therefore lT091bs. ; the pressure upon the W'hole extent of membrane being as many as 58-399 lbs. As the mercury now began to sink, before the whole of the salt was dissolved, there is every reason to believe that the texture of the membrane had suffered so much from stretching, that it be- came damaged, and unfit to make manifest the maximum of the force developed ; the surface of the membrane, too, approached a hemisphere very nearly in figure, by bulging outwards. The above experiment renders it extremely probable that the chemical power of heterogeneous attraction (endosmose, exosmose) exceeds in amount the pressure of one atmos- phere ; but this, in consequence of deficiencies in the apparatus, did not appear. The membrane, which is the part liable to undergo change, requires to be supported in some way, and it ought, at the same time, to present the utmost possible extent of surface, in order to manifest the phenomena in their highest intensity, and with their most striking charac- ters. Probably some such apparatus E 50 FORMS OF CONSTITUENT ELEMENTS. bably some amount of fermentation, forms a thick pultaceous homogeneous mass, the chyme, the fluid constituents of which are for the most part taken up by the veins and absorbent vessels of the intes- tinal tract. The absorbed milky fluid — the chyle — penetrates by the aid of endosmose and the as that represented in fig. 3 would be found the best. A segment of the small intestine of some large animal, secured by ligature at the one end might be filled with concentrated brine, and the barometer tube inserted and secured at the other. This pouch would then be surrounded with a silk net of due dimensions, and plunged into a vessel of distilled water, as usual. Fourth Experiment. — The same apparatus as that employed in the last experiment was filled with saturated brine and a quantity of solid salt, and the mouth of the funnel covered with two folds of bladder, and a piece of firm net. After the lapse of thirty-two hours, the mercury began to run over, and a short time afterwards the rest of it was expelled with force, a quantity of the solution following it. The barometer tube from the under curve measures 374 lines in length ; the depression on account of capillarity is 4 lines. The pressure of the column of mercury, 378 lines in length, was therefore equivalent to 17 lbs. upon the square inch; the pressure upon the whole surface of the bladder amounted to 89‘5 lbs. The endosmotic force was here plainly superior to the weight of one atmosphere. 22. When the solvent or attracted fluid in general, pene- trates from without, through an organised animal membrane into a closed space (21, Example), the phenomenon is entitled Endosmose ; when, on the contrary, the fluid presses from an enclosed cavity or space outwards, then is the occurrence spoken of as Exosmose. Examples of Exosmose. A bladder, or piece of intestine, filled quite full of pure water, and well secured, when laid in a saturated solution of salt, or in contact with any dry readily soluble salt, soon becomes lax and partly empty in consequence of Exosmose. CHYLE — LYMPH. 51 capillary attraction into the minute absorbent vessels (Jigs. 113 and 241), and veins (Jig. 136) of the intestinal villi, which in their final ramifica- tions are covered by the delicate epithelium of the intestine alone. In the same way are the peripheral -%4 b. Let the apparatus described in the “ third experiment ” be so arranged that the funnel shall be affixed, with its base upwards, to the upper end of the barometer tube. Let the in- terior of the tube and the funnel be now filled with distilled water, and the mouth of the latter be closed with a sheet of bladder, as before ; let the funnel be now placed within a second larger vessel, as in Jig. 4, and this be filled with a satu- rated solution of salt, until the surface of the bladder is covered ; the outer saline fluid will attract the water of the funnel and tube, and this will be followed by a column of mercury from the reservoir, the height of which will serve as an index of the power developed, within certain limits , viz. within, or short of, the limits of the atmospheric pressure of the place where, and the moment when, the experiment is made ; for the vapour evolved from the water, and the gases with which it may per- chance be mingled, becoming free, the column of mercury will not follow beyond a certain point. 23. The endosmotic and the exosmotic effects probably diminish with the diminution in the chemical and physical differences of the fluids separated, in the inverse ratio of the square of the times. 24. The effect, in reference to the quantity of fluid that permeates, stands, under otherwise similar circumstances, in direct relationship to the extent of the free membrane. 25. The quantitative effect is always different according to the nature or quality of the interposed substance ; the relative differences connected with this point, however, still require to be ascertained by experiment. 52 FORMS OF CONSTITUENT ELEMENTS. lymphatic vessels of all the external and internal surfaces, and of the interiors of all the solid organs of the body supplied with lymph, which is a trans- parent and yellowish - coloured fluid, and contains effete, and therefore resolved and reabsorbed part- 26. The medium of separation, — the membrane, bladder, intestine, &c. — must have no opening even of microscopic dimensions, otherwise immediate equalisation of the separated fluids ensues without endosmotic phenomena. 27. The more readily the membrane imbibes and transmits water, the better is it adapted to exhibit the phenomena of en- dosmose ; if it be impregnated with oil, fat, resin, and the like, it will shew itself indifferent if brought into contact with watery fluids of dissimilar quality, and no endosmose will take place. The membranous, or other organic septum, therefore, takes an active part in the phenomena of endosmose ; it is, in fact, the cause, by its own inherent power, of the interchange of two dis- similar fluids which takes place until uniformity is established. 28. The finer the membranous septum, the more rapid is the process of endosmose, and the sooner is uniformity in the divided fluids obtained. Thick membranes, however, and several folds of membrane, applied one to another, are better adapted to effect and make manifest striking hydrostatic differ- ences, or to overcome obstacles of other kinds, in consequence of the efficient parts of these supporting each other mutually. 29. Double elective affinities still assert their rights when compound matters having mutual attractions, are separated by septa of animal membranes, &c. Few experiments, however, have as yet been made in this direction, although it is probable that in instituting a series, many interesting results for chemical, physiological, and pathological science would be obtained. 30. All the solid, organised animal structures take up a certain quantity of water, more or less, without being dissolved, as is the case with animal matters which possess no organic structure, such as gelatine, coagulated albumen, &c. — an assur- ance that the hygroscopic and endosmotic property inheres in the matter rather than in the form. On the contrary, under some CHYLE — LYMPH. 53 icles, fluids taken up from without, and certain combined gases ; the lymph also contains upon occa- sion fluids that have been shed, accidentally or in consequence of disease, in preternatural quantity into the tissues and cavities of the body ; and farther, circumstances they part rapidly with so much of their free water that their decomposition is either delayed for an indefinite period, or entirely prevented (fresh meat laid among dry salt first, and then preserved in brine, anatomical preparations kept in spirits, &c.). Does the endosmose proceed with great rapid- ity, by reason of the delicacy and smallness of the structures, which are its seats, as is the case with the blood globules, they can even be seen enlarging under the eye, and finally, in many instances, bursting when the distension goes on unequally. It is, upon the same principle, easy to cause a shrinking of these and other minute organic parts, by merely altering the amount of water and more solid matter in the surrounding medium. This circumstance deserves particular attention in microscopic investigations of all minute structures ; it also requires to be taken into account in my method of determining the specific gravities of the same class of bodies. 31. In fluids which have the same specific gravity as the substances that are the subject of investigation, these last only change in so far as the contact is followed by chemical changes, and the affinity for water depends more on chemical than on physical relations, such as density, &c. The condensation of animal matters, by the contact of other matters or fluids having a great capacity for water, affords us a ready means of rendering much more distinct the outline of objects containing a large proportion of water, and which, on this account, and by reason of their slightly different refractive powers, are examined under the microscope with difficulty. Very soft, and even somewhat diffluent structures, become dis- tinct when they are put for a short time into a solution of com- mon salt, of alum, and the like, previously to their being placed under pure water for examination. To determine the specific gravity of extremely small corpus- 54 FORMS OF CONSTITUENT ELEMENTS. secreted fluids, such as bile, See., elaborated for the purpose of being rejected from the system, when by any accident their excretory ducts become obstructed. § 43. The lymph and chyle are in motion from the periphery of the absorbent system through the conglobate glands towards the principal trunk of the entire system, the thoracic duct, by which they are poured, mingled together, into the general torrent of the circulation at the angle of junction between the left subclavian and jugular veins. The parts that are fitted for so important an end now become constituent elements of the blood, and repair the perpetual expenditure of this fluid in the main- tenance of the body ; the unassimilable parts, on the contrary, are eliminated by the grand depura- tory organs — the lungs, the kidneys, the live.r, and the skin. cles, a small light bottle of clear glass, or a delicate test tube must be procured, weighed accurately, and then, from a few drops to a dram or more of a saturated solution of sugar or common salt, in proportion to the size and number of the objects, having been poured into the bottle or tube, it is to be carefully weighed again. The object whose specific gravity is to be ascertained having been previously weighed (when the object is excessively small the weighing may be omitted), is now to be thrown into the solution in the bottle or tube. If its specific gravity is less than that of the solution, it will swim on the sur- face ; distilled water is now to be introduced by means of a pipette, and mixed with the solution by means of a delicate glass rod, until the object of experiment shews a disposition to sink in the fluid, or, being carried some way under the surface, only rises very slowly to the top ; the specific gravity of the object of experiment and the fluid may now be assumed to be identical. To determine the amount of the specific gravity, let the glass vessel, with its contents, be now weighed (and when CHYLE. 55 Chyle. § 44. The chemical composition, and the de- gree of assimilation possessed by the animal fluids at large, are proclaimed, to a certain extent, by the forms of their microscopic precipitates ; from these, at all events, conclusions in regard to the ex- tent to which the fluids in which they take place are susceptible of organisation, may be safely drawn. If we follow the chyle from the moment of its appear- ance, with an eye directed at once to the chemical and microscopic analysis, and mark the various changes which its chief constituents undergo until they appear as cytoblasts, we perceive the advance from binary to quaternary combinations. And again ; if we watch the cytoblast from the highest point of very minute quantities are employed, the rod that was used for mixing may be left in to prevent any waste), the absolute weight of these, the vessel (the rod, in case it is left in), the object (in case it was of ponderable dimensions), and the concentrated solution first introduced deducted, then is the remainder the weight of the water introduced. Suppose this to be found equal to 3, and the weight of the concentrated solution to have been = 2, and its specific gravity = T1632, we shall then have the following equation (vide 2 and 3), and the specific gravity of the attenuated solution, as well as that of the object, which was the matter of inquiry : — 1 x 1-1632 X (3 + 2) ___ 1-1632 x5 _ 5816 _ , 05Q. X ~ 3x 1-1632 + (1 x2) ~ 3-4896 + 2 — 5-4896 ~ The same end will be attained, and the result come out more accurately, if the fluids are mixed in larger quantity in an areo- metric tube, and the specific gravity at the end ascertained by means of a delicate areometer, or the hydrostatic balance. That the temperature is to be taken into the account, is understood as a matter of course. 56 CHYLE. its vitality, through the successive stages of its degeneration to its chemical and organic resolution and resorption, we observe a corresponding chemi- cal retrocession from quaternary to binary combi- nations of elements. § 45. The chyle, with reference to its quantity, colour, and chemical composition, and to its organ- isation and coagulability, differs in the different families and genera of animals, and also accord- ing to the kind of food consumed ; it also differs essentially in the various parts of the lymphatic system : to such an extent, indeed, does this diver- sity go, that the chyle may be said to undergo in its course a gradual metamorphosis from an uncoagu- lable fluid like milk into blood. § 46. Near the intestine the chyle consists of water, in which a little albumen, a variety of salts, and other simple and more compound matters, are dissolved, and a multitude of oil-globules are sus- pended ; to the presence of the latter is owing its resemblance to new milk.* The salts are partly * Numerous observations have persuaded me that in car- nivorous animals the opacity and white colour of the chyle are due to the presence of infinitely minute particles, of which neither the size nor the form can be distinctly recognised by the best instruments. That these particles may be of an oily na- ture, there is some reason to believe ; but they appear to me to be quite distinct from the oily globules, for the minute particles in question present an uniform appearance, and constitute the base, or ground, of the chyle, from whatever part of its course the fluid may be obtained; and the oily spherules with the granules are contained in this ground, which may be regarded as quite peculiar to chyle. See the Observations on Chyle, &c., in the Appendix G. G. CHYLE. 57 those which are commonly encountered in the ani- mal fluids, partly others accidentally introduced along with the food. Besides salts, indeed, all the substances soluble in water, which are introduced into the stomach, are apt to be — are in fact — absorbed. In the fresh and healthy chyle of the intestinal absorbents, the albumen is in a state of complete solution, — it forms no granular precipi- tate. Owing to the absence of fibrine, the chyle of the peripheral intestinal absorbents does not coagu- late. Examined under the microscope, it is distin- guished from fresh milk only by the striking diver- sities, in point of size, presented by its oil-globules C fig- 23). § 47- In the afferent or peripheral absorbents of the intestines, the fibrine increases continually in quantity as the mesenteric glands are approached. This increase in the quantity of fibrine appears to take place partly at the expense of the albumen, which loses water, partly of the oil-globules, which become continually fewer and smaller ; in the neigh- bourhood of the mesenteric glands, consequently, we remark a commencing precipitation of albumi- nous granules.* After the fluid has passed the mesenteric glands, and through the whole of its subsequent course, this precipitate becomes ever * In the carnivora I have uniformly observed the granular particles, about -^^th of an inch in diameter and in all respects resembling the globules of the Thymus, to be much more abundant in the mesenteric glands than in chyle obtained from any other part of its course whatever. To observe this, it is only necessary to open an animal when the chyliferous vessels are distended, to obtain some chyle from one of the 58 CHYLE. more and more abundant, and acquires new forms, which will be more particularly mentioned by and by, the oil-globules still diminishing continually both in number and size. § 48. In. the mesenteric glands, some portion of the dissolved albumen must be changed into fibrine ; for the chyle from the vessels advancing from these glands towards the central duct, and from this duct itself, now become considerably more transparent and of a pale reddish yellow colour, coagulates when abstracted from its vessels, and by and by separates into a limpid, serous fluid, and a clot or coagulum, — a consistent gelatinous-looking vitreous mass, which, examined microscopically, is found to include albuminous granules, each surrounded by a delicate film of oil. The granular, and now truly fibrinous coagulum* (_ fig. 15), if kept moist, and suffered to undergo the ordinary chemical decom- position, becomes diffluent, and resolves itself into a kind of serous lymph ; the mass, when dried, forms a transparent, brown, horny - looking substance, which is insoluble in water. The serum contains the albumen and the salts in solution, and a pro- portion of the albuminous granules in suspension. lacteals of the mesenteric glands, or from a cut into its sub- stance, and compare this chyle with that procured from any of the vessels between the mesenteric glands and the termination of the thoracic duct. See the Observations on the Chyle, and on the Fluid of the Thymus and Lymphatic Glands, in the Ap- pendix— G. G. * The fibrine of chyle differs considerably from the fibrine of blood, for the former is remarkably less prone to the putre- factive process than the latter. — G. G. CHYLE. 59 § 49. Mingled with the albuminous granules, the central lacteal vessels, at some short distance from the glands, contain a number of extremely delicate, scarcely - coloured lymph corpuscles, as the organic precipitate of the more highly- vitalised fibrine. These lymph corpuscles are, in fact, cytoblasts, — - blood-globules in process of formation ; and in number, dimensions, consistency, and red colour, they go on increasing continually in their progress towards, and course through, the thoracic duct to its final termination (jig. 7 )•* In the same measure and proportion, the coagulability of the chyle, and the firmness of the coagulum formed, go on increasing. In animals that have been kept long fasting, the fluid in the lacteal vessels does not differ, in point of composition and appearance, from the lymph ordinarily contained in other portions of the absorbent system ; there is here an utter ab- sence of the conditions upon which its peculiar characters and appearance depend ; it consists but of simple juices pumped up from the alimentary canal, and the resolved particles that have already * In the horse, Mr. Lane observed that the rosy tint of the chyle from the thoracic duct was due to the presence of the red particles of the blood. (Ancell’s Lectures in the “Lancet,” 1889- 40, v. i. p. 150.) Mr. Siddall and I remarked the same fact. But the blood-corpuscles of the thoracic duct were mostly irre- gular in form, viz., angular, granulated, indented, or jagged at the edges. There were also many corpuscles of the regular shape, but these were uniformly a little smaller than the common blood discs, as represented in Mr. Gerber’s figure. The au- thor’s description seems to be entirely drawn from the chyle of the horse. — G. G. 60 LYMPH. performed their part in the structures from which the vessels lead. § 50. Tiedemann and Gmelin found the follow- ing solid constituents in chyle : — 1, albumen ; 2, a kind of salivary matter ; 3, a species of osma- zome ; and 4, salts, viz. acetate, carbonate, phos- phate, a little sulphate, and a large quantity of muriate of soda ; also, a small quantity of potash ; and, in the ashes after incineration, carbonate and phosphate of lime. In a dog which had been fed upon starch, sugar was detected by the same phy- siologists in the chyle ; and, upon one occasion, I discovered undecomposed starch in the chyle of a horse, which reacted in the usual way with iodine. Lymph. § 51. The lymph, in different parts of the body, and in different circumstances and conditions of the economy, is of still more various constitution in every respect than the chyle. In general, the lymph is of a yellowish colour in the healthy body ; that of the spleen is often reddish and transparent ; sometimes it is as pure as water ; but, by reason of its dissolved elements, it is always more viscid and sluggish than pure water. Lymph only coagulates when, in addition to its other constituents, it contains living fibrine, which is an element not encountered in a general way in the peripheral parts of the lymphatic system, but only towards its central por- tions. Albuminous globules present themselves in variable numbers, and sometimes they are wanting entirely ; the same is the case in regard to oil- globules, — sometimes they occur, sometimes none BLOOD. 61 can be discovered. The lymph is mixed in the thoracic duct with the chyle, and here the mingled fluid has a pale lake tint ; or it is poured directly into the venous system, in various parts, — a fact which can be verified in the horse in almost every part of the body. Foreign unassimilable sub- stances taken up with the lymph as with the chyle, and also effete and waste particles that have already done their office, are seized upon by the different depuratory organs in the course of the circulation, and by them thrown out of the system.* Blood, t § 52. The blood is the product of the chyle and the lymph ; it is contained in the heart and blood- vessels ; of an intense red colour, J sticky to the touch, to the naked eye it appears as a homogeneous fluid ; it has a peculiar odour, which, however, dif- fers in different animals ; and it has a saltish and what is called faint taste. The specific gravity of the blood varies between 1*045 and T06l ; its temperature in the healthy mammal varies from about 96° to about 99° F., +31° to +32° R. ; it generally shews weak alkaline reaction ; its quan- tity, in proportion to the rest of the body, differs * [For some additional observations on the Chyle, and on the Fluids of the Lymphatic and Thymus Glands, see Ap- pendix.] -j- [See Appendix for Mr. Gulliver’s Observations on the Blood Corpuscles.] 4 This, at least, is the case among the vertebrata, — hence called red-blooded animals ; invertebrata have generally, but not invariably, colourless blood. 62 BLOOD. notably, according to the genus, species, age, sex, size, and general condition of the animal examined, and is always determined with difficulty. By Valentin’s very ingenious mode of determining the ratio of the blood to the other parts, it would ap- pear to constitute between one-tliird and one-fourth, or something like three-sevenths of the whole.* The blood is indispensable to all the vital mani- festations ; it, therefore, appears with the earliest traces of life in the embryo, and increases in quan- tity with the evolution and growth of the animal, — previously to birth, at the expense, first, of the vitellary matter of the ovum, and then of the ma- ternal blood ; after birth we have seen provision made for its formation out of the fluids, the chyle especially and the lymph, brought to it by par- ticular orders of vessels contrived to this end. * Valentin’s plan of proceeding is as follows : — A small quantity of blood is taken away from the external jugular of an animal of known weight. Whilst the absolute weight of the blood abstracted is determined, a known measure of blood-warm distilled water is slowly injected by the orifice of the vein to- wards the heart. Some minutes afterwards another portion of blood is withdrawn and carefully weighed. The two quantities of blood are now evaporated in dry air till the residue ceases to lose weight; from the degree of attenuation of the blood effected by the injected water, the previously contained mass of blood can be ascertained by the following formula of Professor E. b x c Volmar : x = (l^c + d. a Absolute weight of the remainder of the blood first removed. c Absolute weight of the remainder of the blood diluted with water. b Weight of the injected water. d Weight of the blood originally contained in the body. BLOOD. 63 § 53. The blood which is propelled from the ventricles of the heart proceeds in two directions, — the one through the lungs, the other through the body at large, in either instance to revert to the heart again, from whence it set out. The vessel, or artery, which proceeds from the heart to supply the pulmonary or lesser circulation, and the vessels, or veins, which lead back the current from all parts of the body to the heart of the adult man and mam- mal, contain a dark blackish red-coloured blood ; the artery, again, of the greater or general circu- lation, the aorta and its branches, and the veins which return the blood from the lungs, are filled with a bright or crimson-coloured blood. O § 54. The dark venous blood at its entrance into the heart, mixed as it is with the chyle and the lymph, contains more foreign matter, and a larger proportion of carbon and water than the arterial blood. These various substances are lessened in quantity, or removed under the action of the lungs, the liver, and the kidneys. Venous blood has a stronger smell, and it coagulates more slowly and less firmly than that which is arterial. The blood of the portal vein, which has the distribution of an artery, is often somewhat turbid, and occasionally of a chocolate colour ; it coagulates less completely than any other blood, and the clot is extremely diffluent. The blood in the venous spaces of the spleen has many of the characters of that of the portal system, and is moreover somewhat more viscid or consistent. § 55. Albumen, fibrine, hematosine, extractive matter, salts, and water, are the principal com- 64 BLOOD. pound chemical constituents of the blood; in the ashes after incineration, especially of the hema- tosine or red colouring matter, a little oxide of iron is met with. § 56. The organic elements of the blood are discovered by the aid of the microscope. These consist especially of extremely minute globules — the blood-globules, suspended in the liquor san- guinis as a menstruum. In such quantities do these globules occur, particularly in the carnivora, that they seem to exceed the mass of the fluid in which they swim. Other elements of the blood are separated nuclei of blood-globules and albuminous granules. In the blood of the frog, single very minute entozoa have also been discovered. ( Va- lentin.) § 57. The blood-globules of the different classes of animals differ in size and form; in the same spe- cies of animal, however, they are alike. The blood- globules are specifically heavier than the blood- liquor. Blood-globules begin to make their ap- pearance in the chyle, and it is probable that they are also formed in the blood itself. In the ma- jority, probably in the whole of the vertebrata, they are flat, in the form of a round or elliptical red disc {figs. 1 to 6). Those of man and the mammalia look like thick coins, or microscopic muffins or cheeses {figs. 4, 5, and 6, 4,). Like all cytoblasts, they in- close in their middle a nucleus of the same general form as the globule, or approximating more to the globular or lenticular shape. This nucleus is generally colourless ; in one case firmer than the investing cell, so that it appears with its true BLOOD. 65 figure, in another softer than the envelope, when it is apt to lose fluid by exosmose, and to shrivel ; or otherwise, it has a less refractive power than the cell, and then it looks sunk in, so that the entire globule has some resemblance to a garland, or small circular puckered pad.* The blood-globules and their nuclei are elliptical in fishes {fig. 1), amphi- bia {fig. 2), and birds {fig. 3). § 58. In the dry blood-globule of birds (pigeon), the edge of the shrunk nucleus forms an elliptical raised border, in the middle of which, when a sec- tion is made of it, a more compact, thicker nucleus projects {fig. 6, B 3.) In the frog, the nucleus, evenly rounded, projects on either side of the general disc, like a portion of a sphere of smaller diameter placed upon one of larger diameter {fig. 6, 2.) In the spider I observed the blood-globule in the shape of a meniscus {fig. 6, 1). § 59. The size t of the blood-globules varies * The blood-globules, like all soft microscopic objects, un- dergo very rapid changes in their forms, apparently in con- sequence of endosmose and exosmose ; they swell up in water, become nearly globular in figure, and then burst. It is im- possible, therefore, to use plain water for the purpose of atte- nuating or isolating the animal fluids and elements, which are the subject of microscopic observation. [R. Wagner particularly recommends the filtered serum of the frog’s blood for this pur- pose. Vide Physiology, &c. by Willis, p. 3. Weak solutions of salt or sugar, and urine, however, answer indifferently well ; but all addition must be especially avoided when it is intended to measure the corpuscles, or to observe their true forms. Even the serum of the blood of one mammal reacts injuriously on the blood-corpuscles of another. Vide “ Lond. and Ed. Phil. Mag.” for Jan. 1840, p. 25 ; and Feb. 1840, p. 105. — G. (?.] j- See Mr. Gulliver’s Observations, Sect. I. in the Appendix. F 66 BLOOD. greatly, particularly in different classes of animals, as a comparison of the figures 1, 2, 3, and 4, which are magnified about 450 diameters, will shew at a glance. In the human subject, the blood-globules are from the 300th to the 250th, and the nuclei about the 400th of a Paris line in diameter. In the horse, the blood-globules vary from the 400th to the 240th, and their nuclei are about the 450th of a Paris line in diameter. The lymph corpuscle of the same animal is about the 480th of a Paris line in diameter. § 60. The husk, or capsule, of the blood-globule, is like the nucleus, transparent, but it includes the hematosine, or colouring principle of the blood. In one case, it appears as a delicate cuticular vesicle, which, besides the nucleus, incloses a viscid fluid ; in another, and more generally, it presents itself in the guise of a soft, elastic, and, externally, red-coloured husk, or capsule, which immediately invests the clearer nucleus. The tint of colour exhibited is various — bright, in the globule of arterial blood, dark-red, and somewhat streaky, in that of venous blood. The shell, or capsule, of the blood-globule, is the bearer of the carbon from all parts of the body through the heart into the lungs, and of the oxygen from the lungs through the heart to every part of the body. Venous blood brought into contact with oxygen out of the body, becomes of a bright-red, just as it does within the body ; and arterial blood, introduced into a jar of carbonic acid gas, but particularly of carburetted hydrogen gas, acquires the deep tint of venous blood. BLOOD, 67 § 6l. The nucleus of the blood-globule* is the part in the structure which, in every respect, is the most puzzling ; not only is it of ditferent sizes ab- solutely, but it is so relatively to the shell, or cap- sule, even among mammals : let the human blood, represented in figure 5, and the blood of the horse, depicted in figure 4, be but compared, and assurance of this fact will be obtained. The nucleus of the blood-globule of the adult mammal resists the action of acetic acid, whilst the envelope becomes perfectly transparent and invisible, perhaps is even completely dissolved 'under it.t The hlood-globules of the foetus of the mammal, as somewhat larger than those of the adult animal, their nuclei are in the same proportion of greater magnitude, and are but little affected by acetic acid. § 62. The number and characters of the blood- globules are found to vary in different diseases. In chlorotic subjects, they are of a very pale colour ; and, in reference to the general mass of the blood in anemic states, as after repeated losses of blood, or when there is an excessive demand upon, or use of, the fluid, such as takes place along with extensive suppuration, and when its solid consti- tuents are inadequately renewed, from the want of sufficient supplies of wholesome food, for instance, their quantity is diminished. On the other hand, the globules in relation to the fluid constituents of the blood are increased in quantity after exudations * [See Observations on the Blood-corpuscles, Sect. IV. in the Appendix.] f Under the action of iodine, however, it often becomes visible again. 68 BLOOD. of the liquor sanguinis (plastic exudations, the formation of false membranes), and of the serum (watery exudations and acute dropsies), when the blood is also relatively of a deeper colour than usual.* In plethoric persons, the quantity of blood circulating through the vessels is excessive. If the liquor sanguinis becomes extremely watery, the blood-globules seem to suffer a kind of maceration, and lose a portion of their cruor by solution. Be- sides all this, the blood undergoes great and signal changes in numerous diseases ; in fevers of bad type, in cholera indica, &c., it becomes pitchy, and will not coagulate ; in purpura hemorrhagica, it sets like thin currant jelly, &c. ; and, in addition to all this, under certain circumstances, it appears changed to a deadly animal poison, as in anthracion, or malignant pustule, in rabies, hydrophobia, &c. § 63. In the minuter currents, the blood- globules have the effect of producing an optical interruption to the continuity of the stream ; by which the circulation of the blood becomes visible in the more transparent parts of the bodies of living animals, viz., in the extremities of young spiders, in the fins of fishes, in the gills of the larva; of the newt and frog, in the tail of the water- * [Some of these statements are to be received with caution. In diarrhoea and cholera the blood does certainly become pitchy, both in consistence and colour; but in acute dropsies nothing of the kind occurs as a general rule : if, in these cases, there be a certain loss of serum into the general cellular tissue of the body, there is accumulation of this fluid to a far greater extent within the blood-vessels in consequence of the suspension of the functions of the kidney, skin, and, indeed of every emunctory of water from the system.] BLOOD. 69 newt ( fig . 6, A), in the web of the frog’s foot, in the mesentery of the smaller mammalia, &c.* In the smallest blood-vessels of all, the blood-corpus- cles follow each other in single files ; and the diameter of the final conduit, therefore, stands in a determinate ratio through the entire series of the animal kingdom to that of the globule which has to be transmitted.! § 64. During the unimpeded coagulation of the blood, the blood-corpuscles apply themselves fiat one to another, so that they form elongated cylin- ders {fig. 8).t § 65. Nearly allied, and of like origin, to the lymph and blood-corpuscle, are the exudation-cor- puscle, the true pus-corpuscle, and the corpuscle of ulcerated surfaces, — the ichor corpuscle. Exu- dation-corpuscles always appear in the vital liquor sanguinis, when this comes into contact with the * This most interesting and instructive spectacle of the cir- culation is best enjoyed by making use of low powers, and having a wide field. There is nothing in nature more beautiful than the spectacle that then presents itself. j- If this be true, as it probably is, how remarkably the intermediate blood-vessels must differ in size ! It would be interesting to examine them in the Proteus ; and still more to compare the size of the capillaries of the Napu musk-deer ( Mosel ms javanicus, Pallas) with those of the mammalia having comparatively large blood discs. The subject, too, gives addi- tional interest to observations on the size of the blood-corpuscles in different animals. See my Appendix on the Blood Cor- puscles.— G. G. ! To procure columns of blood of this kind for microscopical examination, let a plate of glass be wetted with blood as it is flowing from the vessel; then incline the plane so as to let all drops fall off, and to have the surface merely moistened. 70 BLOOD. living tissues of the body out of the blood-vessels. The globules of unhealthy suppurating surfaces are blood-globules which have escaped from vessels de- stroyed by the ulcerative process, and been altered by the action of the ichor or watery fluid amidst which they are contained.* Pus-globules arise when exu- dation-globules are only mediately in contact with the living tissues. Of these cytoblasts we shall have more to say by and by. § 66. The lymph, or fluid (blood-lymph, liquor sanguinis, s. plasma), in which the blood-globules swim, and the perpetual expenditure of which is supplied by the lymph and the chyle, is a clear, yellowish-coloured fluid, from which, when it is left at rest, the fibrine separates by coagulation, after a variable interval, the limits of which may be stated at from one to twenty minutes. The separation is more quickly accomplished in carni- vorous and strong animals than in frugivorous and weakly subjects. With the included blood-globules the fibrine, after its coagulation, forms the crassa- mentum, or clot, which is by so much the more solid as the means of its previous solution — the serum — escapes completely from it, which happens particularly in the case of vigorous men, and animals of the male sex, and, under all circumstances, in re- gard to arterial blood. The superior surface of the crassamentum consists of a thin layer of pure fibrine with a few oil-globules disseminated through it. § 67- When coagulation takes place slowly, the specifically heavier blood-globules sink in the liquor * See note at page 28, and at page 41. — G. G. ORIGIN, ETC. OF ELEMENTS. 71 sanguinis, so that a relatively thick layer of pure fibrine covers the surface of the clot, and constitutes the sizy, huffy, or inflammatory coat , or crust* If freshlv-let blood he beaten with a rod, or a mass of crassamentum be washed, the fibrine is pro- cured by itself in the form of white fibrous bundles, or of a tough fibrous mass ( fig . 15, A). Fibrine that has coagulated in the form of a hyaline mass, as it does when it forms the huffy coat, by and by becomes granular (fig* 15, B). If it sets in im- mediate contact with the living tissues of the body, it is, in due season, organised ; — exudation- cor- puscles (fig* 205, 1, 2, 3) are formed, which, arranged one by another upon the living surfaces, constitute exudation membranes (fig. 206), or, more remotely from these, undergo transformation into productive pus-globules (fig. 9? b) ; and these, with serum and albuminous granules, form true laudable or healthy pus. ORIGIN, EVOLUTION, AND ULTIMATE STRUCTURE OF THE LIVING CONSTITUENT ELEMENTS OF ANIMAL BODIES, AND OF THE ANIMAL TISSUES. § 68. A course of microscopical researches into the nature of the different morbid secretions and exudations, particularly of the transuded products of inflammatory action upon the surfaces of internal * Upon the artificial formation of this layer, see the explana- tions of the figures from 11 to 14. Some excellent observations on the formation of the buffy coat will be found in Dr. Davy’s “ Physiological and Anatomical Researches,” vol. ii. p. 46. — G. G. 7 2 ORIGIN, ETC. OF ELEMENTS. cavities, led me, among other particulars, to investi- gate the subject of apparently accidental secondary organisations. I followed the secondary organ- ising process in the products of suppurating wounds ; the primary formative processes I traced in the impregnated ovum. I shall find no better or fitter place to make known the more important results of these inquiries than the present ; and these I shall, accordingly, ingraft in the immediately following paragraphs, which treat of the genetic relations and developement of the different tissues. But let us, as a means of securing clearer compre- hension of the matters to he stated, begin with a consideration Of the Motions and Changes of Place of the Fluids. § 69. In vessels. In the normally constituted healthy living body, the blood is found in constant motion in every part of the vascular system, so that each individual blood-globule may, by possibility, perambulate every point of the greater and lesser circulation many times ; the chyle and the lymph, on the contrary, perform but the single journey from the point of their absorption through the intervening lymphatic vessels and their appertaining glands, to that at which they are poured into the blood. The same thing obtains in regard to the motions of the various secreted fluids ; they are conveyed directly, and, once for all, from the point of their elaboration, through the nearest secretory canals and excretory ducts to that at which they are to be ORIGIN, ETC. OF ELEMENTS. ^3 made use of specifically, or to be discharged from the system. Gravitation of the Fluids . §•70. All the fluids of the body gravitate by their weight towards the most depending parts of the close cavities, and even of the tissues generally, where they would accumulate, were they not main- tained in parts that lie higher by some superior force, or were they not continually brought back to these, as the blood is by the force of the heart, the chyle and the lymph by the contraction of the vessels, adhesion to the parietes of these, and the in- terchange of compression and relaxation through the action of neighbouring muscles, particularly those belonging to the respiratory system.* In the healthy living body there is little evidence of mere mecha- nical gravitation of fluids, even to the most depend- ing parts : but in the dead body the case is differ- ent ; there the fluids immediately begin to gravitate to those parts that are on the lowest level, where they accumulate and are met with in greatest quantity.! * [And unquestionably, also, and probably of more avail than all the vis a ter go generated by the perpetual afflux of fluids, in virtue of the heterogeneous affinity developed at the extremities of the lymphatic system.] f [ A human dead body, in a leaden coffin closely soldered, does not undei’go decomposition to any extent, for, it may be, twenty, thirty, fifty, or more years ; but the whole of the fluids fall through it : a dryish, mummified mass is found lying in a depth of an inch or more of a reddish serous fluid.] ORIGIN, ETC. OF ELEMENTS. 74 Hydrostatic or Passive Congestion. § 71- Even during life a depending part of the body receives more blood than when it is placed horizontally, or raised above the level of the source whence it is supplied. The legs, as the most de- pending parts of the body, are, therefore, subject, in the greatest degree, to this passive or hydrostatic congestion ; and we have constant evidences of its occurrence in the frequently overloaded and varicose veins of the lower extremities, which disappear when the legs are laid horizontally, or raised to a very small angle with the rest of the body. Stoop- ing the head is also familiarly and universally known to be followed by a preternatural accumulation of blood in that part, which is in a great measure the effect of simple gravitation.* % [Despite this simple and familiar fact, however, some of our physiologists have denied that there could by possibility be more blood contained in, or circulating through, the brain at one time than another. The brain, it has been said, is incom- pressible, and, filling exactly the hollow sphere of the skull, can- not have more blood circulating through it at one time than another. But the brain is far from being incompressible ; it is, on the contrary, highly elastic, and, therefore, compressible. Were it as incompressible as water, however, it may still be subjected to pressure. If we adapt a forcing-pump to a hollow sphere full of water, and endeavour to throw more fluid into it, though we find this impossible, the contents of the sphere are obviously in a very different condition from what they were befoi’e we began to force. So it is with the cranium : the shut sphere of the skull is still in communication with the powerful forcing-pump, ORIGIN, ETC. OF ELEMENTS. 7 5 Active Congestion. § 7^. Transient dilatations of the capillary vessels (probably induced by diminished contractile powers, the effect of a kind of temporary and limited paralysis), also occasion local increment in the quantity of blood ; a congestion of this kind is apparent, and passes rapidly off, in the blush of modesty or shame ; we have instances of more per- manent morbid congestion, accompanied with a stasis of the blood, and the known phenomena of reaction, in inflammations. NORMAL ESCAPE OF THE FLUIDS FROM THE VESSELS. General Endosmotic Transudation. § 73. Nutrition, secretion in glands, and the like, without free or open-mouthed terminations of the heart ; and if the injecting power and the quantity of blood sent forward exceed the capacity of transmission in the same time, there will certainly be pressure exercised on the brain. The anatomical arrangements in connexion with the circulation through the cranium ; the provisions made to pre- vent the arteries from expanding in their calibre, in other words, from transmitting blood in excess ; and, on the contrary, the beautiful contrivance by which the sinuses are defended from suffering any diminution in their areas, — the arteries reaching their destination through tortuous , unyielding , bony canals ; the sinuses braced out in three directions, (as few as were adequate, and not more than were necessary to keep them constantly per- vious), all give us assurance that, under certain circumstances more blood might circulate through the brain at one time than another.] 76 ORIGIN, ETC. OF ELEMENTS. vessels, presume an exudation and transudation of the constituents of the blood to take place through the parietes of the vessels. Endosmotic transference of heterogeneous fluids, separated from each other by solid tissues, certainly occurs through every part of the body during life as well as after death ; and this in consequence of one of the universal chemi- cal or physical laws, which has been designated that of heterogeneous attraction. That such a process is constantly going on, is made obvious among other phenomena by the communication of colour from one part to another : all the parts in the neighbourhood of the gall-bladder are dyed yellow or green ; and other parts, lying in contact with such organs as the liver, the spleen, &c., which are extremely rich in blood, are regularly stained of a reddish or brownish hue ; this occurs to a greater extent in the dead body, indeed, than in the living, from the serum after death dissolving some portion of the colouring matter of the blood ; but, still, it undoubtedly takes place, to a certain amount, in the living body also.# * “ A popular objection to this view,” says Mr. Mayo, in his Outlines, “ is founded upon the fact, that on opening the body of an animal immediately after death the parts adjoining the gall-bladder are not tinged with bile. But it is easier to imagine that the bile is in this case washed away by the circulating blood, or carried off by the lymphatics as fast as it exudes, than to sup- pose a new principle in the living body competent to suspend the common laws of imbibition by porous substances.” — G. G. ORIGIN, ETC. OF ELEMENTS. 77 MORBID ESCAPE OF THE FLUIDS, PARTICULARLY OF THE BLOOD FROM THE VESSELS. Extravasation . § 74. When, in consequence of a fall or a blow, a part of the body is bruised, or injured in its inti- mate texture, its vessels ruptured, &c., but without breach of the surface, we have extravasations formed, — effusions of blood, of milk, See. into the tissue of the organ injured. Exudation.* § 7 5. On all the external and internal surfaces of the body there is a constant escape, in conse- quence of transudation, of one or more of the con- stituents of the blood, or of some peculiar fluid, with which these surfaces are bathed, or by which the cavities they form are filled in a greater or less de- gree. The fluids transuded in this way are liable to be greatly increased in quantity under particular circumstances. The cutaneous perspiration, the watery fluids poured into the serous and mucous cavi- ties, the gastric and intestinal fluids, &c., are products of normal and necessary functions of the kind alluded to. These exudations may, also, become morbidly altered, both in quantity and quality : poured out in excess into the shut sacs of the body, such as the * The term exhalation is only applicable under circum- stances where the atmosphere or some gaseous fluid is present, as is the case, for example, with the skin and the mucous mem- brane of the lungs. Exhalation, therefore, can never occur in the serous sacs, or other close cavities of the body. 78 ORIGIN, ETC. OF ELEMENTS. ventricles of the brains, the pleurae, the pericardium, the peritoneum, and the general subcutaneous and inter-organic cellular tissue, they form dropsies ; poured out upon the surfaces of open passages, such as of the nose, the lungs, the bowels, &c., they form profluviae of different species, — coryza, pulmonary catarrh, diarrhoea, cholera, &c. Morbid Exudation in consequence of Inflammation. § 76. In the serous and synovial sacs, in the cellular tissue, &c,, it is common to observe inflam- mation terminating in effusions of different kinds ; in one case, of the watery or serous element of the blood ; in another, of simple plastic matter, when the liquor sanguinis exudes without the blood- globules ; and in a third, of sanguinolent matter, when the liquor sanguinis exudes, tinged with the colouring matter of the blood, or actually mingled with a smaller or larger proportion of blood- globules.* This last form of exudation forms the transition to hemorrhage. Morbid Exudation of Blood ( Hemorrhage ). § 77- When the blood escapes from open vessels, externally or internally, it is spoken of as external or internal hemorrhage. * Blood-corpuscles are repeatedly found, quite unaltered in appearance, on the mucous surfaces, when no solution of con- tinuity whatever can be detected in any of the vessels. Mr. Siddall and I saw a remarkable instance of this in the horse. The lining membrane of the trachea was throughout coated with a deep red viscid matter, the colour of which was found to be owing to numberless blood-discs. These, however, soon became ORIGIN, ETC. OF ELEMENTS. 79 § 78. In the fluid of serous exudations it is usual to find the albuminous granules of albumi- nous fluids, and when the greater part of the serum is again removed by absorption, should this occur, the crystals of different salts. When the quantity of exuded serum is considerable, or the effusion continues long, it is apt to penetrate other contiguous and more dependent parts, and so to produce a partial or more general dropsy.* § 79- After plastic exudations, or mingled serous and plastic exudations, a yellowish, turbid fluid is found in the affected cavity, having fine flocculi, of a pale yellow colour, floating about in it, or precipi- tated upon, and perchance adhering to, the bound- ing parietes in every part. The serous membranes, cleared of these deposits, are found unaltered, and granulated, and very irregular in form, and then scarcely or not at all visible, from solution of their colouring matter. The escape of the blood-corpuscles from the capillaries, under certain circumstances of disease, will not appear so surprising, if we con- sider the remarkable softness and elasticity of the corpuscles, and the facility with which they change their form, becoming bent, compressed, or elongated, so as to adapt themselves for the pas- sage of any unusually narrow channel. After passing the ob- struction, they recover their usual shape with singular rapidity. Some of these temporary alterations in the blood-discs may often be very well observed when they are mixed under the microscope with currents of grosser particles, as of pus-globules. See the Observations on the Blood-corpuscles of Mammalia, Sect. III. in the Appendix. — G. G. * [Even partial dropsy must be regarded as an extremely rare occurrence from such a cause : it is very doubtful whether general dropsy was ever seen as its consequence. The cause which is at work producing the local accumulation of fluid is then inducing a general accumulation.] 80 ORIGIN, ETC. OF ELEMENTS. the injected vessels that appear are not included within, but lie under them. If, instead of the tur- bid serous fluid mixed with small flocculi now men- tioned, larger continuous masses of coagulable lymph are encountered amidst the effused serum, the exu- dation, it may be concluded, has taken place very rapidly. § 80. When the exudation of plastic matter goes on for any length of time, and the quantity of effused liquor sanguinis is considerable, the cavities into which it is shed may be filled with it ; or their parietes, and the organs they include, — the heart, lungs, liver, intestines, &c., may become covered with thick layers of coagulated fibrine. This, at first, is of a pale yellow hue, and somewhat trans- lucent, and has the consistency of imperfectly coagu- lated albumen. If death occur at this stage, the hyaline substance quickly becomes granular, and, in consequence of chemical decomposition, is dis- solved in the serum. If no fatal event ensue, the characters of the exudation are otherwise altered. § 81. In an animal* debilitated to a great de- gree, the exuded fibrine is discoloured, is greyish or greenish instead of white or pale yellow, as if it were going to change into pus, which, however, it never is ; t under the microscope the matter has * When no particular animal is mentioned, the horse is to be understood as the subject of observation. All that is stated in this and some of the following paragraphs, applies, however, with trifling modifications, to man and the other mammalia. f I have never seen suppuration — the formation of true pus — take place in the shut sacs of the serous and synovial mem- branes where there was no external wound ; I believe that it EXUDATION. 81 all the characters of corrupting fibrine, a sign of approaching death.* never happens. When pus is found in any of these sacs, careful inquiry always shews that it has been produced in tissues which were covered by the serous membranes, and that it has only made its way into the cavities after permeating the membranes. Empyema, therefore, is never a product of the pleura, never an immediate effect of pleuritis, — a title, by the way, which is radically objectionable, inasmuch as the serous membrane itself never participates in the inflammation of the highly vascular cellular tissue which it covers, and is only affected or altered by the morbid processes there going on, in so far as it depends for its nutrition and continuance on the capillary rete, •which lies on the outside of it, and which is, in fact, the tissue that is obnoxious to inflammation. [In 1722 Dr. Simson, of St. Andrews, re- garded pus as a secretion, and Dr. Morgan, of Philadelphia, and Brugmann, of Leyden, promulgated this doctrine through- out Europe. Mr. Hewson especially noticed (“ Exp. Inq.” Part. 2, p. 117,) that pus was often found in the serous cavities, without any erosion or the least mark of ulceration ; and the Hunters insisted on the production of pus, both by the mucous and serous membranes, independently of any bi’each of surface whatever. Indeed, this view of the matter is now, and has long been, generally entertained. — G. G.~] * This is a very interesting fact, and if confirmed would serve to explain the circumstances we observe after opening extensive abscesses, performing the operation of paracenthesis of the chest, &c. Perforation of the thorax is an operation simple enough in itself. So far as the division of parts is concerned, there is no more risk in reaching the bag of the pleura than in opening a vein to let blood ; the same may gene- rally be said in regard to discharging an extensive abscess. But the consequences of either operation are often disastrous ; and this probably from a change induced in the effused matters, that causes them to be felt as foreign by the living parts with which they are in contact. Excitement of a new kind is set up in the seat of the local mischief, and then comes secondary fever with the hectic type, and all the train of disastrous symp- G 82 ORIGIN, ETC. OF ELEMENTS. § 82. If the inflammation ends with the ex- udation, and the disease, and the loss of vital fluids consequent upon it, have not exhausted the strength of the animal, the exuded and coagulated fibrine, under otherwise favourable circumstances, is by so much the more quickly and completely organised as the creature is vigorous.* The exuded serum is gradually removed by absorption, whilst the particles* and masses of fibrine which float loose in it are dissolved. The particles and masses of fibrine which are attached, on the other hand, become of a bright yellow colour, and, examined under the mi- croscope, are found to consist of adhering or con- nected exudation - globules, which are formed in toms that so frequently render the discharge of large abscesses, and especially the operation of paracenthesis of the chest fatal, — the untoward tendency being doubtless increased in the latter instance by the importance of the organ interested. Vide the note < at p. 28. — G. G. * It would appear, however, from some valuable observations by Mr. Dalrymple, that the organisable material of the blood, when effused without direct rupture of the vessels, is more rapidly organised in those conditions of the system denominated cachec- tic than in the more vigorous and robust. In the latter, he is of opinion that inflammations more quickly pass into the suppura- tive or ulcerative stages, while in the former the effusions of fibrine become more rapidly organised, and are apt to remain as persistent structures. Many of his conclusions are deduced from cases of ophthalmic diseases, which are peculiarly favour- able for observation, and in which the rapid organisation of exuded fibrine in cachectic subjects with syphilitic iritis is remarkable as compared with idiopathic or traumatic iritis in more vigorous constitutions. Mr. Dalrymple’s injections seem generally to support his views as to the very rapid organisation of fibrine under the circumstances mentioned. Vide “Med. Chir. Trans.” vol. xxiii G. G. EXUDATION. 83 from twenty-four to thirty hours after the occurrence of the exudation,* when the masses are of a ruddy yellow, t and have acquired such consistency, that they can be peeled off in cohering shreds from the membranes to which they are attached. § 83. Exudation-corpuscles ( Jig . 205) are, in every respect, the same as the lymph-corpuscles. J They generally form many superimposed layers, being laid flat one over another, and so constituting * Nuclei, with or without envelopes, may be found in fibrine as soon as it has set, independently of inflammation. Vide note p. 31. — G. G. f Like that of the chyle in the thoracic duct, this is the almost uniform colour of the fully evolved cytoblast. In those animals whose mature chyle is of a paler colour, the exudation- corpuscles are paler also — an assurance of their identity in all the parts of the body of the animal in which they are examined. f; In mammiferous animals, it has always appeared to lhe that the lymph- globules differ in size, structure, and chemical characters from exudation-globules. The latter are larger, more irregular in size and shape, more spongy or loose in texture than the former. Besides, the exudation-corpuscles generally exhibit two or three nuclei when treated with acetic acid, whereas the lymph-globules are only rendered slightly smaller by this reagent; and the acid either dissolves or makes remark- ably fainter the comparatively thick shell of the exudation- corpuscle, while the lymph-globule becomes more distinct wheu subjected to the action of the acid. It is true that an occasional appearance of a nucleus is presented by the lymph-globules when thus treated ; but this is, for the most part, a single globular pai’ticle nearly as large as the entire lymph-globule, as if produced simply by the most superficial part of the globule being very feebly affected by the acid. The lymph-globules, in fine, in pro- gress of developemenl, may soon become more or less coated 'with fibrine ; but, if examined at an early period, they will be found to resemble in chemical characters the nuclei (nucleoli of Valentin) of primary cells, — a fact which appears to me to be of consider- ORIGIN, ETC. OF ELEMENTS. 84 membranes which bear the strongest possible resem- blance to those composed of the tessellated epithe- lium {fig- 103, b'), when the connecting medium has disappeared, by which the edges of the primarily round corpuscles come into contact, and are thus forced into the shape of polygons. § 84. Some hours later a greater degree of co- hesion, and stronger indications of a fibrous struc- ture, are observed in the exuded mass ; and, under the microscope, an ever-increasing linear arrange- ment of the component globules, which appear more intimately united at two opposite points in one line, by means of the connecting cytoblastema, than any able interest. To make this examination satisfactorily, the glo- bules should be examined in the fluid of the lymphatic glands, or in that of the thymus body. I have kept portions of the latter for weeks in acetic acid without producing any other change in the globules than a slight diminution of size, and an increased distinctness and smoothness of their outline, probably in consequence of the removal of a very delicate commencing fibrinous concretion from their surface. In structure, magni- tude, and chemical properties, the globules of the lymphatic glands and of the thymus are identical. I subjoin, from my notes, measurements, expressed in fractions of an English inch, of the exudation-globules and of the lymph-globules of the horse. The former were obtained from fibrine effused upon the inflamed pleura, the latter from a lymphatic gland of the thigh : — Exudation-Globules. Lymph-Globules. 1-32001 1-2900 > 1-2666-* 1-45721 1-2286J Common sizes. Extremes. l-5333j 1-4800J 1-64001 1-3200 J Common sizes. Extremes. 1-2962 Average. 1-4626 Average. — G. G. EXUDATION. 85 where else {fig- 102, c, d ) is apparent : the rest of their edges is comparatively free. If the cytohlasts were globular at first, they now acquire more of a spindle shape ; the flat ones continue more flattened after their margin has become fusiform, and in a linear direction they represent, in connexion, vari- cose fasciculi, in the enlargements of which the nucleus of the exudation-globule continues visible, and either subdivides into several granules, or has a new nucleolus evolved within it. Betwixt the cellular fibres which have now been formed, there still remains an interposed hyaline substance, so that the masses may be separated mechanically, or torn in any direction, almost with like facility. Under a low magnifying power the cellulo-fibrous mass appears as it is represented in fig. 17. § 85. At the parts where the villi and festoons connected with the free surface of the exudation exhibit a greater degree of cohesion, we also observe the commencement of the transition of the cellular fibrils into round filaments. This transition ap- pears to require either a longer time to attain com- pleteness than the formation of the cellular fibres out of the recent exudation, or the organisation here remains stationary under peculiar and still unknown circumstances, just as it seems to do with reference to the same structures even in the primary tissues of adult animals, — for example, in the sheaths of the soft nerves and more delicate vessels {figs. 102, c ; 103, d ; and 163, b , e). With the progress of the formation of round filaments, the intercellular fibrils get longer {figs. 218 and 219), whilst the fusiform nuclei get smaller, and at length entirely disappear. Occasionally one cell is observed to be 86 ORIGIN, ETC. OF ELEMENTS. connected laterally with another lying near it, and then three intercellular fibres proceed from it {fig. 219, c). § 86. Even before the formation of round filaments, duly ordered blood-vessels make their appearance, and form a capillary net-work, as they do in the intestinal villi. First, transparent arbo- rescent streaks are seen, which push out their in- creasing ramuscles on all sides, to encounter one another, and form a series of reticulated inoscula- tions. But before the vascular rete appears, pale- coloured cytoblasts have been produced, which, after the completion of the rete, pass over into the near- est primary capillary veins, whilst they are pushed onwards by the blood of the nearest primary arte- ries ; and in this way is the circulation established through these secondary formations. The vascular rete is more intricate in the larger villi and festoons {fig. 20), and the distribution here resembles, in every thing, that of the intestinal villi {fig. 136). Here may be distinguished the terminal divisions of the arteries {fig. 21, a ), the terminal divisions of the veins (6), and the further subdivisions of these vessels into capillary arteries (c), capillary veins (aQ, and intermediate or transition vessels {e, e ). In the smaller villi the blood-vessels comport them- selves like those of the gills and toes of the larva of the newt, and those that accompany the isolated single nervous fibrils of the skin ; that is to say, they run simply along the edges of the parts.* * Mr. Liston has given an extremely clear description of the arrangement of the intermediate vessels of granulations, as they appear in the cysts of abscesses and on open sores. In abscesses the capillaries project into the new and adventitious lining mem- EXUDATION. 87 § 87. Long after the occurrence of exudative inflammation, and when all traces of diseased action have subsided, the serous membranes implicated are found thicker and less transparent than proper ; the organs which they cover are also found adhering to one another, and to the parietes of the cavities in which they are contained ; longer and shorter white lappets hanging from the surface of the viscera and containing walls, and strings, broader bands and con- tinuous sheets of false membrane, passing in various directions from the one to the other, and connecting the viscera together, and with the sides of their con- taining cavities. These various accidental structures are all of the same essential nature : they have the general appearance of serous membranes, and con- sist of rounded filaments firmly united by a common vitreous substance (vide Jig. 18, which is a repre- sentation of a mass of connected cylindrical fibrils seen under a low magnifying power). Sometimes the round filaments are but loosely bound together, and entirely correspond in structure with primary cellu- brane, often in straight parallel lines, though the arrangement of the vessels in the granulations on the free surface is distinctly looped and tortuous, with communications between the loops, this vascular arrangement being much like that of healthy secreting surfaces. In a portion of injected ulcer the vessels of the gra- nulations were found to be similarly arranged, but enormously and irregularly dilated or varicose, — a fact which suggests an important therapeutical indication. Mr. Liston has also demon- strated the existence and arrangement of the vessels in the cartilage of diseased articular surfaces, so that the possibility of this tissue being nourished, absorbed, or repaired by its own vessels, can no longer be doubted. “ Medico - Chirurgical Transactions,” vol. xxiii. p. 85. — G. G. 88 ORIGIN, ETC. OF ELEMENTS. lar substance and tendon (vide fig. 19, where a is a representation of the cellular filament, b of the fila- ment of tendon, the fibres being parted or teased out in either case). § 88. The same phenomena are observed in inflammations with plastic exudations of the syno- vial as of the serous membranes ; in the capsular ligaments of joints, therefore, in the bursse mucosae, and in the sheaths of tendons, precisely the same products are encountered. § 89. The same formative processes are also observed in the chorion of the impregnated ovum ; and, indeed, under all circumstances where the exuded living liquor sanguinis or cytoblastema, left at rest in closed cavities, is in a condition to become completely organised ; as, for example, when it is deposited on the parietes of abscesses containing laudable pus, &c. ; and these secondary products of organisation, it is to be observed, are never to be regarded as accidental, — they are perfectly indis- pensable to the repair of any injury that has been suffered, to the maintenance of the individual who has been its subject.* # When, for instance, inflammation of the shut sacs of the body (the serous and synovial membranes) has exceeded the limits at which resolution is possible, or when it has destroyed all capacity in the part to perform its function, then is this ter- mination, by an exudation of coagulable lymph, the most favour- able that can occur ; nay, it is the only one that renders a recovery (which, however, may only be relative) possible : an organisable deposit has become necessary to the restoration of the part, and such a deposit is coagulable lymph ; without its pre- sence the serous effusion of the inflammation nrould become a stagnant, dropsical effusion ; but the newly-formed villi of plastic ORIGIN, ETC. OF ELEMENTS. 89 FORMATION OF PUS, AND REPRODUCTIVE ORGANISA- TION IN SUPPURATING WOUNDS OR SORES. § 90. Simple incised wounds, made with a clean sharp instrument, heal, by what is called the first intention, in the course of a few days — almost of a few hours, when the wounded surfaces can be brought into apposition without dragging, and the reparative process is suffered to go on undisturbed. In this case, the fibrine of the extravasated blood fills up all the smaller accidental hollows in the depth of the wound ; cytohlasts are then produced, these are transformed to cells which acquire a final organisation in consonance with that of the parts injured, and the superficies of the wound is repaired, — the adjacent edges are united by means of a secondarily produced firm tissue, universally known by the name of cicatrix. § 91. Wounds with a loss of substance, gaping sabre-wounds, gunshot and other wounds, where a certain degree of bruising attends the solution of continuity, — wounds, too, that have been filled with foreign substances, dirt, &c., which must be got rid of before they will cicatrize, all heal by suppuration. The process in these cases is as follows : — § 92. After having bled to a greater or less extent, the wound becomes stiff, and painful, and lymph, projecting into the affected cavity, increase the extent of absorbing surface, become vicarious of the functions of the now incompetent membrane, and remove immediately the serum which has become free in consequence of the coagulation of the exudation. 90 ORIGIN, ETC. OF ELEMENTS. dry ; an exudation of the liquor sanguinis is then established from the entire extent of surface, and this goes on incessantly till the injury is repaired. The fibrine, as it coagulates on the raw surface, forms exudation-globules, or cytoblasts, many of which cohere in layers, and compose the false membrane that finally invests the entire superficies of the sore. The layers of globules in most immediate contact with the living tissues become cells, which then undergo further transformation, in accordance with the nature of the structure to he reproduced ; those layers of globules, again, which are most remote from the living parts become pus-globules, and these, mingled with a small quantity of serum, compose true or laudable pus, which, on the one hand, indues and protects the focus of organisation, separating the granulating surface, as the surface of a wound in process of repair by suppuration is called, from external agencies ; and, on the other, forms the soft, mild medium in which reproduction goes on from the more remote parts towards the centre, and by which foreign substances are detached and removed from the sore. Pus. § 93. The exudation-globules, which lie beyond the vivifying influence of the surface of the wound, and exposed to the action of external agencies, can- not he expected long to retain their vitality ; these globules, therefore, forsaken, as it were, by the organising principle, begin to degenerate in their organisation, and to suffer changes in their chemi- cal constitution, whilst those that continue in imme- PUS. 91 diate contact with the living structures of the body advance in their organisation : those globules that are cast loose then die — mors vitce origo. § 94. On the exudation-globules that are free, a number of delicate lines, radiating from a centre, are first perceived, which divide their peripheries into from six to eight (seldom more) segments ; these lines become more and more distinct, and the capsule appears as if it were torn or cleft, hut without sepa- ration of parts ; in many globules, too, the nucleus now appears to incline to fall into from two to four pieces {fig. 9, a ; fig. 10, ?, k) ; the originally reddish yellow colour of the globules fades,* the segments of the envelope and the divisions of the nucleus, which had been linear and sharp in appearance, become rounded off till they appear like aggregated granules, whilst the pus, now completely formed, acquires a greenish yellow hue. True pus-globules, formed in both these ways, may still be found, here and there, hanging together like the cells of the tessellated epithelium ; they are specifically heavier than serum, appear under the microscope somewhat larger than lymph, exuda- tion, and blood-globules (they generally measure from the Ti^th to the yi^th °f a Paris line in dia- * The colour of microscopic objects fades in the ratio of the magnifying power, in consequence of the apparent subdivision of the matter in which it inheres, and its diffusion over a larger extent of surface ; but on the other hand, colours appear under the microscope which had escaped the naked eye entirely ; thus fine threads and single fibres of cotton, highly magnified, appear en- tirely blue ; colours are usually perceived as they present them- selves to the naked eye. 92 ORIGIN, ETC. OF ELEMENTS. meter), are of a yellowish colour, and usually mingled with oil-globules and albuminous granules ; they are often seen besprinkled with albuminous granules, which are then by many mistaken for integral parts of the globules, their larger proper granular sub- divisions,* which together give the pus-globules the appearance of lenticular or muffin-shaped cush- ions tucked in at different distances by lines radi- ating from a common centre, being overlooked (vide fig. 10, /, the pus-globule from the flat surface, h from its edge : the variety here represented is that with quadrifid nuclei). By and by the granules separate to a greater extent ( fig . 9, S), so that the corpuscles resolve themselves into their elements ; for old pus consists, in great part, of these more or less com- pletely isolated granules.t § 95. When pus, in its various stages of form- ation, is kept in a glass, at rest, for about ten hours, it divides into two layers ; t the upper of these is the * The form and elementary organic constitution of the pus- globule become exceedingly distinct in a solution of common kitchen salt. f I am unacquainted with the form of pus-globule described in this paragraph. — G. G. 1 This is not always the case. The pus of which the parti- cles are shewn in fig. 258 was taken from an abscess at the end of February, and now (April 1) the matter is throughout homoge- neous, never having had any supernatant serum. When a quantity of this pus was dried and heated on paper no greasy stain was produced. In some observations which Mr. Siddall and I made on the generation of infusory animalcules in the fluids of mammals, we could detect no animalcules in pure blood, however long it might be kept, — not even when putrefaction was far advanced. But they were soon generated when water was added either to PUS. 93 more diffluent, and is of a pale yellow or very light brown colour, from translucent to transparent, and occasionally covered with oil-globules ; this is the serum of the pus. The under-layer is more slug- gish, of a yellowish green, or greenish grey colour, in different cases, and now more, now less in quan- tity than the serum ; this layer consists of the pus- globules, mixed with a little serum, and occasion- ally a number of crystals. § 96- Chemically analysed, pus gives different results, according to the quality and age of the fluid, — according as it is true pus or false pus, and as it is mature or immature. In giving an analysis of pus, chemists should never fail to state the source, and all the circumstances connected with the speci- men examined. The younger the pus, the larger is the quantity of fibrine it contains (transition- cytoblasts) ; the more mature the pus, the larger is, in general, the quantity of fatty matter which it contains. This retrograding fluid, consequently, from its origin to its perfect developement, forms a direct contrast to the chyle, in point both of organic and chemical constitution. The chyle is at first a kind of oily emulsion, and fibrine only appears in fresh or stale blood. The same observations apply to the animal fluids generally, judging from experiments with serum, pus, synovia, &c. The observations were not sufficiently numerous to be quite satisfactory, and they are merely mentioned here as suggesting a curious subject which appears to be deserving of further inquiry, especially in connexion with the theory of gene- ration. It seems not improbable that common water contains the rudiments of animalcules, which blood does not. See what the author says of entozoa having been discovered in the blood of the frog, § 56, p. 64. — G. G. 94 ORIGIN, ETC. OF ELEMENTS. it as it undergoes elaboration ; pus, on the con- trary, at first is fibrine mingled with a watery fluid ; it is in a great measure an oily emulsion at last. Relative Admixture, in point of Quantity, of the Three Compound Chemical Principles, and the Advance in the Progress of the Assimilation of the Chyle.* In the afferent or peri- pheral lacteals(from the intestines to the mesenteric glands).. In the efferent or cen- tral lacteals (from the mesenteric glands to the thoracic duct) ... In the thoracic duct . ' Fat, in maximum quantity (numerous fat or oil-globules). 1 Albumen, in minimum quantity (few or no albuminous granules). '^Fibrine, altogether wanting. ( Fat, in medium quantity (fewer oil- globules). I Albumen, in maximum quantity (nu- merous granules). ' Fibrine, in minimum quantity (in gra- ^ nules, without the form of cytoblasts)* 'Fat, in minimum quantity (few or no oil-globules). 1 Albumen, in medium quantity. Fibrine, in excess (cytoblasts, lymph, and corpuscles)4 * In this view the water, salts, &c. are not taken any account of, these being presumed to be constant but less essential ele- ments here. + This cannot be an universal law, for I have occasionally seen a delicate though very distinct clot in chyle obtained from the afferent lacteals G. G. J More globules exist in the chyle of the mesenteric glands than in that of the thoracic duct, or, indeed, of any other portion of the lacteal vessels whatever ; at least, I have always found this to be the case when the lacteals and thoracic duct were turgid with chyle. The globules here mentioned are not fatty, but similar to those contained in the fluid of the thymus. See note, p. 57 ; and Appendix. — G. G. PUS. 95 Decline in the Progress of the Formation of Pus. In pus beginning to be formed In pus well advanced in its formation .... In pus quite .mature / Fat, in minimum quantity (no oil - 1 globules). Albumen, in minimum (few granules). Fibrine, in maximum (cytoblasts, exu- \ dation-corpuscles). 'Fat, in medium (few oil-globules). Albumen, in excess (granular pus- globules. Fibrine, in minimum (no new cyto- . blasts). ' Fat, in excess (numerous oil-globules). Albumen, in medium quantity (gra- nules of decompounded pus-globules). . Fibrine, absent. § 97. The corpuscles of pus, before they fall clown into granules, are acted upon by acetic acid, in the same manner as the lymph, blood, and ex- udation - corpuscles ; the denser nucleus remains nearly unaltered, whilst the granular capsule becomes perfectly transparent, or is dissolved ; and when this happens, the component granules of the nu- cleus separate from one another.* The nucleus and * The action of acetic acid on pus-globules is not always the same. If these be quite recent when mixed with the acid, their envelopes will instantly disappear ; but if the same pus be kept for some days, the action of the acid will be much fainter ; and in pus from chronic abscesses the globules frequently exhibit scarcely any change when treated with the acid, as was the case in the matter represented in fig. 258. Indeed, the operation of several re-agents on fibrine becomes more feeble in proportion to its age as a separate matter, and to its compactness. Acetic acid scarcely affects the old fibrine of an aneurismal sac, though recently clotted fibrine is quickly swollen, made transparent, or 96 ORIGIN, ETC. OF ELEMENTS. cover of cytoblasts, also differ in their chemical composition, a fact which might have been inferred from their optical diversities, each possessing a dif- ferent refractive power ; nevertheless, both of them appear to be mere modifications of one substance, viz. albumen, and entitled by Koch,* puriwn ; by Miclielottijt puruline ; by Gueterbock,t pyine ; by J ordan,§ fibrous matter ; and by John,|| modified albumen. Pus-globules may be obtained pure by dissolved by this reagent ; and the matter of an old crude tubercle seems to resist the action of the acid altogether, which is by no means the case with recent tubercular deposit. Fibrine, therefore, would appear to undergo modifications in its chemical properties after its separation from the blood ; and the ready solubility in acids of the most superficial parts of cells and cytoblasts probably arises from the comparative newness of the fibrinous matter of which the outer parts are composed. It should be remarked, however, that the solubility of fibrine in acetic acid is questionable, for many fibrinous parts which dis- appear on being mixed with the acid may be brought into view again by the addition of iodine. But this consideration does not affect the fact of the different properties of recent and old fibrinous matter. Some interesting observations on the action of vinegar are given by Dr. Davy in his “ Researches,” vol. i. p. 376, from which it appears that the solvent power of this acid on the animal textures generally is very limited. — G. G. * F. Koch, dissert, de Observationibus nonnullis Microscop- icis Sanguinis Cursum et Inflammationem spectantibus atque de Suppuratione, adjecta Analysi Puris Chemica. Berol. 1825. f Rossi et Michelotti, Analyse de Pus. Memoires de Turin pour les annees 1805 a 1808. J Gueterbock, de Pure et Granulatione Commentatio Phy- siol. Berol. 1837. § Jordan, Disquisitio evictorum Regni Animal, ac Vegetabil. Elementorum. Gcettingae 1799, p. 40, unb u. GfrellS d)em. 2tnnaterp 1801, et. 9, @. 208. || Sofjn/ them. Unterfudjungen. SScrt. 1812. S3b. 2, <3. 120. PUS. 97 repeated washings with distilled water ; they contain very little inorganic matter ; according to Pearson, hut the -g-J-g-g-th part, insoluble in alkalis, is soluble in concentrated acids ; infusory animalcules * are only observed in the pus that is old. § 98. As it is obvious, from what precedes, and from the results of the analysis immediately to be quoted, that not every puriform fluid is true pus, and that true pus itself differs according to its age, maturity, the circumstances under which it has been formed, &c., it follows that those ana- lyses only are of any value which are accompanied by some account of the case, and the subject in which the pus was produced. Vogel, t from the numerous analyses of pus which he has published, assigns the following proximate principles as the essential constituents of the fluid : — I. Pus-corpuscles or globules. II. Serum, composed of 1. Water. 2. Animal substances, viz. — a. Fat. b. Osmazome. c. Albumen in solution. 3. Inorganic acids and bases, united into inorganic salts, viz. as constant ingre- dients, sulphuric acid, and hydrochloric acid ; each united with lime, potash, soda, magnesia, and ammonia ; and, as occasional ingredients, phosphoric acid, * See note, p. 92. — G. G. •j- SSogcI, q3pv)ftoXo9tfd)=patt)otogtfdE)e Unterfucfiungen fiber ©iter unb ©iterbilbung unb bie bamit cerwanbten ffiorgangc. ©rlangen/ 1838. H 98 ORIGIN, ETC. OF ELEMENTS. acetic, and lactic, and other organic acids. As a secondary product, the result of incineration, carbonic acid. 4. Scilica and oxide of iron. V Analysis of Pus by J. Martins, Erlangen. Human pus, from an empyema, the consequence of pleuro- pneumony. The matter, of which five measures were dis- charged, was pretty consistent, of a yellowish green colour, and without smell ; examined under the microscope by Professor Rudolff Wagner, it was found to contain numerous granules, from the 200th to the 300th of a Paris line in diameter (these, in all probability, were true pus-globules). Tested chemically, it was found neutral, — it did not affect vegetable blue colours. It consisted of the following : 1. Bases: — Lime, potash, soda, magnesia, and ammonia. 2. Acids : — Phosphoric, hydrochloric, lactic. 3. Indifferent matters : — Fat, albumen, osmazome, gelatine, besides water. Analysis of Pus by Gueterboch : — the Pus from an Abscess in the Human Breast. 1. Water 864 2. Fat only soluble in boiling alcohol L6 3. Matters (fat and osmazome) soluble in cold alcohol 4-3 4. Matter soluble neither in hot nor in cold alcohol (albumen, pyine, pus -corpuscles and granules) 7*4 Loss 06 100 The salts in 100 parts of pus amount to 0*8 Of which there are soluble in water 0*7 Consisting of — Chloride of sodium, in large proportion PUS. 99 a s ^ W Sulphate of soda “ Carbonate of soda < Hydrochlorate of potash (chloride of potassium) >■ Hydrochlorate of lime (chloride of calcium) [ Substances soluble in nitric acid 1 0-1 Consisting of — Phosphate of lime Phosphate of magnesia Carbonate of lime Iron, a trace. Analysis of Pus by Koch , ivithout any Indication of its Source , or the Circumstances attending its Production. 1. Water. 2. A peculiar substance ( purium ) contained in the globules. 3. Albumen. 4. Mucus. 5. Osmazome. In the ashes — Chloride of sodium, phosphate of lime, carbonate of potash, phosphate of potash (soda?), sulphate of lime, carbonate of lime, phosphate of magnesia, oxide of iron, scilica. Analysis of Pus from the Uterus of a Mare , according to Goebel. The fluid of a yellowish white colour, opaque; specific gravity, 1-019; sluggishly fluent, smooth; of a faint, unpleasant smell, neutral ; sinking to the bottom when shaken up with water, coagulating when exposed to heat. Albumen 7-20 Uncoagulable, gelatiniform animal matter 0*94 Free acids, sulphate (and lactate?) of potash, common culinary salt, phosphate of lime, magnesia, protoxide of iron, and scilica 0-35 Water 91-33 100 ORIGIN, ETC. OF ELEMENTS. Analysis of Pus from the Frontal Sinus of a Mule , according to Dumas.* This pus reddened litmus paper, formed an emulsion with cold water, from which, in the course of a few days, a white floccu- lent matter precipitated. Raised to the temperature of 70° cent, it formed a white granular coagulum, which, washed with water, exhibited all the properties of an albuminous substance, with the exception that it dissolved readily in hydrochloric acid. The water used in washing it, evaporated, smelt unpleasantly of • cheese ; the dried residue was a yellow extract, which powerfully attracted moisture from the air, and dissolved in alcohol, with the exception of a few albuminous flocculi : this solution, diluted with water, was not rendered turbid ; it contained a free acid, a large quantity of hydrochlorate of soda, and a little phosphate of ammonia. 997 parts of this pus consisted of — Water 820 0 Albumen 165-0 Animal matter, soluble in alcohol and water (osmazome?); phosphates and hydrochlo- rates, and free lactic acid f 12-5 * Repert. Gen. d’Anat. et de Physiol, t. iii. p. 47. 1827. f The specific gravity of pus is a point not adverted to in the text, but which it is as well to notice. According to Dr. Davy, there is considerable variation in the specific gravity of pus, as will appear from the following tabular view of his results : — Kind of Pus. Sp. Gr. Good quality and ordinary consistence : from a a case of empyema complicated with S 1028 pneumathorax Not quite equable : from an abscess in the thigh Pretty equable, of moderate consistence : from an abscess of the axilla, in con- > 1029 valescence from erysipilas From the arm, in convalescence from erysi- pelas of a dangerous character FALSE PUS. 101 False Pus. § 99* We are constantly meeting with secreted and exuded fluids, both in man and among the lower animals, which, without more particular ex- amination, and, in especial, without an appeal to the microscope, are mistaken for true pus.* These fluids are, indeed, extremely like pus when viewed by the naked eye, and in chemical composition are not very different from it. Nevertheless, they are produced otherwise than true pus, and their nature is different. On the other hand, we occasionally observe matters deposited upon, and poured over, surfaces which look very unlike proper pus, and which yet are either veritable pus, or a substance most nearly allied to it in constitution. § 100. It is the fluid already described, the healthy or laudable pus of writers, which alone is pro- duced under the conditions necessary to reproduction in the animal body : I have, therefore, sometimes spoken of it under the title of reproductive pus ; and as the corpuscles which compose it generally consist of seven granules, it might also be designated the From an abscess in the back of a young man 1040 Rather thicker than the healthy pus of an 'i abscess: from a large cavity of the lung l 1042 in a fatal case of consumption From a vomica in the lung, in another fatal case of pulmonary consumption “ Researches, Phys. and Anat.” vol. ii. p. 466. — G. G. * With the exception, I believe, of Dr. Addison, patholo- gists in this country have generally, of late years, described softened fibrine as pus, especially with the view of explaining the theory of suppuration. See note, page 28. — G. G. 102 ORIGIN, ETC. OF ELEMENTS. seven-granular pus. The corpuscles of this fluid, previously to their resolution, always belong to the nucleated corpuscles ; * they are degenerating cyto- blasts. In this constant peculiarity of the pus- corpuscle lies the safest criterion for distinguishing pus from other fluids bearing a nearer or more dis- tant resemblance to it ; every fluid which is without the peculiar corpuscles indicated, and which never fail in the pus of healthy wounds, however much this fluid resembles pus in appearance, is not pus in reality, and is incapable of aiding the vital processes of repair and reproduction in which the true pus- globule, in its first state of exudation-globule, is the immediate agent. § 101. The purifiorm mucus, which is secreted in the last stage of catarrhal affections, varies according to the kind and amount of reproductive process which the mucous membranes implicated require for their restoration. Should the mucous glands and the mucous follicles he altered in a less degree than the epithelium, which after catarrhs is always reproduced afresh, then the discharge, be- sides the usual mucus-corpuscles and granules {fig. 25, B), contains a large addition of newly-formed small lenticular cells {fig. 216), instead of the usual older elements of the epithelium, which are large squamous granulated cells {fig. 193, a; fig. 220) or cylinders {figs. 24, 46, 48, 223). In these newly-formed small lenticular cells the nuclei * The granules which are included in the nuclei of cells, and which are spoken of by Muller, Schwann, and others, under the title of nuclear corpuscles (Kernkdrperchen), I name, with Valentin and o.thers, nucleoli (Kernchen). PURIFORM MATTERS. 103 are often recognised with difficulty, and this makes them look extremely like large exudation-corpuscles ; from which, however, as they differ essentially, they are soon distinguished. Among these young epi- thelial cells, we occasionally observe true pus-cor- puscles ; this happens when any part of the mucous membrane has suffered so much as to require repro- duction. § 102. Puriform milk seldom occurs without an admixture of actual pus-globules, which then pro- ceed from abscesses of the milk-gland. The puriform sediment of the urine is, in differ- ent cases, a matter of very different composition ; it only contains true pus-globules when the repro- ductive process is going on in some part of the kid- neys, bladder, &c. When we meet with true pus- globules in the urine, therefore, we may he certain that the uropoetic system has suffered a breach of continuity * in some part.t What has now been said * See note, p. 81. — G. G. f The rejection of undissolverl pus by the urine from other parts of the system than those that lie in the immediate track of that fluid, is as untenable a notion as that of purulent metastasis without solution of the corpuscles and rupture of the vessels. As, in fact, speaking generally, no reception of the globules of pus into the circulating fluid is possible without rupture of vessels, it is in vain looking for any thing of the kind in the blood in ordinary cachexies and dyscrasies. Pus-globules, as such, can only occur in the blood (and if they did, it would not follow that they were to be excreted in the same shape by glands) when there has been a wound or injury inflicted, — when a solu- tion in the continuity of the tissues has occurred, which has necessarily implicated veins and lymphatics, as is the case in sup- purating sores, in phthisis, and where there are abscesses of inter- nal organs, the lungs, the bowels, &c. In cases where a deteri- 104 ORIGIN, ETC. OF ELEMENTS. in regard to the puriform characters of mucus, of milk, and of urine, applies to all the other secreted fluids. The Fluids of Bullae, Phlyctenoe, and Pustules. § 103. In the vesications produced by scalds, blis- ters, the inunction of the tartar-emetic ointment, in superficial aphthae, in the smallpox and cowpox erup- tions in their first periods, &c. &c., the fluid exuded oration of the juices appears to depend on the absorption of pus, it is not pus-globules as such that deteriorate the blood, but the chemical qualities of the pus which has been taken up, inde- pendently of every thing like form, in its component elements. Finally, pus absorbed from any one part of the animal body can never be deposited in the shape of pus, and by metastasis in any other part, inasmuch as pus once detached from the living surfaces that produced it is a matter no longer possessed of vitality, and incapable of evolving cytoblasts ; pus-globules once resolved into their elements, or dissolved, cease obviously to be pus : and this they must be, as we have seen, before they can be absorbed in quantity into the system, except in those cases in which a substance like pus is formed in the immediate channels of the circulation, as it is liable to be in phlebitis in all its shapes. [In phlebitis it is difficult to conceive how pus can enter the circulation, for the veins are shut up by clots between the diseased and healthy parts. A vast number of cases, usually comprehended under the term phlebitis, would appear rather to be examples of stagnation, clotting, and softening of fibrine. As to the occurrence of pus-globules in the blood, certain large white globules may be detected under the microscope in the blood of all the vertebrate animals; and in some febrile affections pus- globules, or their similitude, occur in unusual numbers in the blood. A small quantity of pus introduced into the blood, into the cellular tissue, or into a serous cavity, generally predisposes m a remarkable manner to the suppurative action, although other foreign bodies, as iron nails, or common shot, do not pro- duce this effect. I have made many experiments on this subject PURIFORM MATTERS. 105 is a scrum with albuminous granules,* so long as the texture of the cutis remains uninjured, because the reproduction of the cuticle takes place without suppuration. Should the cutis suffer, however, then suppuration and cicatrization become neces- sary. It is on this account that we first observe true pus with pus-corpuscles produced in the suppu- rative stage of smallpox, when, through the intensity of the local inflammation and the contact of the smallpox virus, the subjacent corium is injured in its texture. In the modified or serous smallpox, the suppurative stage does not occur, in consequence of the local inflammation wanting power to cause destruction in the true skin. Fluid of Ulcers ( Ichor ). § 101. In the discharge of sores, true pus- corpuscles are only discovered when there are parts of the ulcerated surface upon which healthy exudation, and the formation of cytoblasts are pro- with dogs and cats. In pus produced by inflammation within the animal, the bad effect seems to be prevented by the assiduous manner in which nature isolates the matter from the neighbour- ing tissues ; and in those cases in which the suppurative action becomes general, affecting many organs, as in the so-called metastases, there is commonly little or no deposition of coagu- lated lymph circumscribing the purulent deposits, whether on the surface of a stump after amputation, or in the substance of an organ. In fine, it appears to me to follow, from the experi- ments just mentioned, that the contact of pus with the blood or tissues predisposes to suppuration generally — “a little leaven leaveneth the whole lump.” — G. G.~\ * [The fluid of a large blister, set aside in a clean vessel for a time, will often, if not generally, be found to have a delicate coagulum formed in it. ] 106 ORIGIN, ETC. OF ELEMENTS. ceeding, as means of repairing the breach of con- tinuity. If this be not the case, — if the entire ulcerous surface be in an unhealthy state, then the secreted serum contains ichor-corpuscles, with gra- nules, in variable quantity ; and when the sore is of the phagedenic kind, larger or smaller detached shreds of the structures implicated, in the shape of filaments and fibres, cartilage-corpuscles, and the like ; occasionally, also, oil-globules and crystals. This fluid is of very different colours in different cases, and is generally much thinner than good pus. An [ill-conditioned and unhealing] sore is a wound with a surface incapable of throwing out or organ- ising plastic lymph, bedewed with an altered serous fluid — ichor, in technical language — destructive of any exudation that may be produced. This ichor seems even to irritate and eat farther into the tender surface of the wound, and to cause the destruction of the most superficial vessels, which leads to the dis- charge of small quantities of blood, which is imme- diately discoloured and so much changed that the liquor sanguinis rarely coagulates save in granules, and the blood-globules appear variously puffed up or crumpled together, superficially corroded or broken down into irregular pieces. The blood-globules thus altered are denominated ichor-corpuscles {fig. 9, d ; fig. 10, c, d ) ; they are very commonly covered with granules loosely or more intimately attached to them ; they are, probably, better studied in the discharge of glanders than in any other, this consisting in great part of them. When the unhealthy surface of a sore is turned into a fresh wound, either by the removal of the surface PURIFORM MATTERS. 107 with the knife or the destruction of this, together with the discharge by means of the actual or poten- tial cautery, under otherwise favourable circum- stances reproductive suppuration is established. Contents of Cysts, or Morbid closed Cavities* § 105. It is not uncommon to meet with matters of very different descriptions deposited in cysts or membranous sacs in various parts of the body. The including sacs are organised in different degrees, and are to be regarded as of common origin with their contents ; both alike are products of a process of transudation, and they, therefore, hear the same relations to each other, and generally, as do the villous adventitious membranes of serous cavities and the naturally shut sacs, in the various stages of their organisation (§79-87; .fig- 17-21)- The contents may exhibit every degree of consistency and organ- isation, and present all the forms of the elements of the animal body. § 106. The contents of accidental cysts are in one case serum, with a variety of substances in solution, or diffused through it. Besides granular matter, crystals of different salts are frequently met with, particularly in the cysts of glandular struc- tures, rhomboidal horny lamina?, often in such quan- tity that the fluid glistens with something of a pearly or metallic lustre. Very commonly, also, another substance, — the cyst-corpuscle, which is very apt to * The heterogeneous contents of an ovarian cyst are exhi- bited in fig. 256. Some distinct cells appear containing minute spherules, and there are many oval nucleated corpuscles, smaller than the cells. — G. G. 108 ORIGIN, ETC. OF ELEMENTS. be mistaken for the pus-corpuscle, is encountered in the fluid of cysts. Cyst-corpuscles are generally completely round, hut little transparent, of a yellow- ish green, a greyish or brown colour, from the 300th to the 15th of a line in diameter, and they consist of granules rolled together without a nucleus ( fig . 9? c ; fig. 10, /, G. G.’s Jig. 26l, c). They, therefore, belong to the granular or aggregation-corpuscles ; and they not only resemble the mucus-corpuscles {fig. 25, B), and the aggregated pigmentary corpuscles {fig. 32, 1), but often seem to form a medium of transition into these last. Under certain circumstances, the nature of which are unknown to me, these corpus- cles are flattened and lenticular, and then scarcely larger than the fiftieth of a line in diameter {fig. 10, e,fi). These bodies are, also, often seen covered on the surface with the granules of the fluid.* § 107. When cysts contain what appears to be blood, the fluid is generally of the consistence of blood that has been stirred or beaten ; which, indeed, it greatly resembles : the fluid is not, however, blood in the strict sense of the word ; it appears rather to be the product of a continued exudation of the liquor sanguinis. The exudation-corpuscles are then of a chocolate colour, as is the serum also, — larger than blood-corpuscles, and, in point of organisation, they * The comparison of the pus-globules of the frog with its blood-globules is very important in respect to the theory of the formation of pus. They bear a very close resemblance to the flat, aggregated corpuscles above described ; but they contain a distinct granular nucleus; in diameter they measure about five- sixths of that of the blood-globules. [I have never succeeded in establishing suppuration in frogs. However injured, the partsproduced no purulent matter. — G. G .J PURIFORM MATTERS. 109 correspond with those of serous cavities.* Such cysts, of considerable size, are frequently found in the ovaries of women and the domestic animals, in the kidneys, &c.t § 108. Encysted abscesses, or purulent deposits of glandular and other parts, contain in one case true, and in another false, pus ; in a third case, again, the included matter looks like mashed potato, and consists of exudation-corpuscles^ which often remain long unchanged after the removal by absorp- tion of the serum, as in scrofulous glandular swell- ings, and in false or cytoblast tubercles, which, in the ox particularly, occur so commonly, and sooner or later go on to suppuration, — in the lungs, for instance, where they then form vomica. § 109. The induration of glandular organs especially, in consequence of plastic exudation into * In the body of a female 48 years of age, which was ex- amined by the author in the year 1837, two enormous cysts of this kind were discovered, one of them lying between the trans- versus and internal oblique abdominal muscles, and containing upwards of twenty Bernese measures of fluid ; the other and smaller being situated between the diaphragm and transverse arch of the colon. The parietes of these cysts were composed of an organised layer of fibrinous matter half an inch in thick- ness, covered internally with extensive projecting villi, and also with many hydatids ; the free-corpuscles in the fluid of these last measured the 170th of a Paris line in diameter. The iso- lated portions of the exudation were also organised, and shewed the general chemical properties of fibrine ; they were dissolved by acetic acid, and again precipitated by hydroferrocyanate of potash, alcohol, and heat. f The fluid from an ovarian cyst of a mare weighed in one case 1 1 pounds ; that from a cyst in the kidney of a fatted bullock, 14 J pounds. 110 ORIGIN, ETC. OF ELEMENTS. their tissues (infiltrated tubercle), often consists for a long time of exudation - corpuscles, and re- main in the shape of a nearly dry substance after the resorption of the serum with which it was at first abundantly mixed ; it is much disposed to run into suppuration, but is susceptible, by a further process of organisation, of conversion into true fibrous tubercle, which composes a cicatriform sub- stance,— a substance like the cicatrices of cutaneous wounds, and consists of cellular and granular fibres, occasionally of imperfectly formed filaments.* As the result of an analysis of the caseiform tubercular matter, undertaken by M. Hecht, 6 grammes were found to consist of 14 decigrammes of albumen, 12 decigrammes of gelatine, 18 deci- grammes of fibrine ; water and loss, 16 decigrammes. Organisation of the Exudation in Suppurating Wounds ( Granulation, Cicatrization ). § 110. As already stated (§ 31-42), the form- ation of cytoblasts is the general principle of genesis or origin, and the formation of cells the general principle of evolution in all the elementary parts of the animal organism possessed of determinate forms. Albumen, as the matter susceptible of vitality, quickened and endowed with formative power in the shape of liquid fibrine, is, however, the one universal genetic fluid, — the cytohlastema from which and in which animal cytoblasts are produced, the seed and * From the above, it is evident that the author uses the word tubercle in another and a much wider sense than that in which it is employed in this country. Vide farther on this subject, § 310 et sequent . — G. G. GRANULATION. Ill tlie soil at once, as it were. The same substance, in all probability, exists in a modified condition in the vital fluids of plants, especially at those places where the formation of cytohlasts is going on. The visible manifestation of the common principle of life connected with organic matter is the formation of cells included one within the other ; that of or- ganic matter susceptible of vital endowment is the formation of granules. The presence of life in or- ganic fluids is proclaimed by the enduring presence of ternary and quaternary compounds. § 111. In all essential particulars we find a repetition of the process which we have already fol- lowed in the organisation of the plastic exudation of serous cavities (§ 82, 88), in the formation of the substance of cicatrices ; there is this difference, how- ever, that in the organisation of the new product com- plexity must be expected, by so much the greater as the tissues to be repaired are of dissimilar nature, and that the particles and masses of fibrine, mingled with the serum, instead of being dissolved as they are in close cavities, are transformed or degenerate into pus, — an event which also happens in regard to the exudation of shut cavities, so often as the air finds access to them soon after exudation has occurred. When adventitious, morbid cysts, which have ex- isted for years, enclosing all the while fluids of a nature very different from pus, are opened, suppu- ration generally immediately sets in ; the lining membrane of the cavity is thrown off, and the space now changed to an open wound is gradually closed by granulation. As the access of the atmosphere, generally speaking, proves favourable to the occur- 112 ORIGIN, ETC. OP ELEMENTS. pence of reproductive purulent formation, so true pus is usually only found in situations in contact with the air,* whilst the contents of close cysts, filled with puriform matter, are generally no more than aggregation or cyst - corpuscles (§ 35, and 106). Exudation from the surface of a wound goes on con- tinually until it is completely healed up ; and as organisation begins immediately in the exudation, the fibrine first poured out, and nearest the exuding surface, must be at once completely organised, whilst exudation is still going on in the interior of the sore upon the granulating surface. With regard to the mode in which exudation takes place, the plastic lymph coagulates as fast as it is thrown out, and in a few minutes composes a layer of unorganised vitreous substance, investing the entire surface of the wound. Half-an-hour later this is found transformed into an imperfect epithe- lium,— the wound appears covered with a delicate membrane, made up of exudation-corpuscles arranged side by side, and under the microscope appearing tessellated, or like a piece of pavement formed of polygonal pieces ; the nuclei of the several corpus- cles are also now perceived, and the new membrane acquires a passing resemblance to the appear- ances seen in fig. 4Tf. This most immediate layer now becomes transiently true epithelium, whilst the nucleus, at the same time and under circumstances * In a preceding page the author asserts this more un- equivocally. Dr. Davy could obtain no air from the pus of abscesses (“Researches, Phy. and Anat.” vol. ii. p. 462); and I am not aware that it has ever been proved that air has access to many suppurating sacs in which true pus is produced. — G. G. GRANULATION. 113 with the precise nature of which I am not yet fully acquainted, undergoes three different alterations, viz. 1, it becomes granulated ; or, 2, a clear vesicle is formed on the cytoblast ; or, 3, a nucleolus appears in the nucleus, rounded cells are formed about the exudation-corpuscles, and the exudation or cytoblast- coverings become cell-coverings, which, were they permanent, would compose a true epithelium {fig. 21 5, c). The - formation arrived at this stage is already an integral part of the body where it is evolved, being included within the common bound- ary of the organism, and participating in its general states and operations. The cytoblasts which are remote from the surface of the wound, in the mean- time retrograde (§ 93) ; their enveloping membranes crack (§ 94, fig. 206), and the masses into which they divide become granules (§ 94) ; the nucleus farther splits into from two to four granules, and the cytoblast membrane is transformed to a pus- membrane {fig. 9, b), which is now foreign, and felt to he foreign, to the organism. The pus- globules separate and become diffused through the serum ; they fall, at length, into granules, and are gradually removed from the wound, whilst the general mass of pus included within it, from the granulating surface outwards, exhibits the various transition stages from the perfect exudation to the ripe pus-globule. § 112. The cellular layer, which now covers the surface of the wound, as a living, organised portion of the body, is competent to carry on the pro- cess of transudation and reparation ; over and in i 114 ORIGIN, ETC. OF ELEMENTS. contact with it a new layer of exudation-globules is thrown out, which, undergoing the transformations just described, come in their turn to form a mem- braniform cellular layer ; over which a layer of pus- corpuscles is deposited as before, and so the process goes on. § 113. In the successive evolutions of these cel- lular laminae, the newly-formed unite with the older cells to form a continuous cellular substance, which is by and by converted into various kinds of cica- trix,— cellular substance, bone, tendon, &c. ; or, at all events, a matter which replaces cellular tissue, hone, tendon, skin, &c. Granulation. § 114. The cellular substance produced in this manner forms what arc called the granulations of wounds ; in the course of repair and suppuration going on granulations are scattered over the surface of a healthy healing sore, in the shape of blood -red rounded points, very much as we see the surface of a close cauliflower covered with minute warty tubercles. The bright red colour of healthy granu- lations does not depend on the numerous newly- formed vessels, filled with blood (§ 86), alone ; the cells themselves, especially those most recently evolved, are of nearly as deep a red colour as the blood-globules ; and the superficial bleeding which follows even the slightest touch of the granulating surface, does not proceed from blood shed from the newly-formed vessels only : the red fluid, besides blood -globules shed in this manner, consists in GRANULATION. 115 part also of ruddy cytoblasts, newly developed red- coloured cells, pale granules, and reddish serum.* It is a common property of animal cytoblasts, that they present a red colour on their first forma- tion, and in contact with oxygen ; but this hue they lose again, whether they advance to perfect developement and become integral parts of a living tissue, or die and degenerate, as they do when they are cast loose and form pus-globules. § 115. A thin perpendicular slice of the newly- formed substance of a suppurating wound generally shews the different stages of transition from the momentary vitreous substance of the superficies, and the layer of exudation-corpuscles immediately be- neath it, to the almost perfectly formed supple- mentary tissue of the deeper portions ; the different lamime, however, are never so distinct here as they are in other situations — for example, in the second- arily engendered cellular substance composing the adhesions and false membranes of close cavities lined with serous surfaces {fig. 17> 18, 19.) The newly-formed vessels present themselves in such re- lative connexion with the nearest uninjured parts of the body, that they appear to form a normal portion of the peripheral vascular expansion ; the newly- formed vessels, and probably nerves also, compose ter- minal festoons or loops, and form a kind of foundation for the granulations in the same manner very nearly as the terminal loops of the vessels and nerves do * It is difficult to say whether this colour of the cytoblasts is acquired from contact with the atmosphere, or is original ; it is next to impossible to make observations upon the formation of granulations with the exclusion of the atmospheric air. 116 ORIGIN, ETC. OF ELEMENTS. for the papillary bodies of the cutis. Of these ter- minal loops, the representations in jigs. 92, 93, 97> and 98, are calculated to convey a very good idea. The relations of the newly-formed nerves are traced with much more difficulty than those of the newly- produced blood-vessels. Cicatrization. § 116. When the cavity of the wound is at length more or less perfectly filled up by the granu- lations and the supplementary tissues they have formed, the last layers of exudation poured out undergo transformation into an imperfect kind of corium, and finally, to a cuticle or epidermis of the same description. In place of an exuding wound we have, in the end, a deeper and then a paler violet-coloured depressed cicatrix. Even after com- plete cicatrization, the newly-developed tissues are never so determinate and distinct as the primary tissues in their immediate vicinity. The various supplementary tissues are, generally speaking, formed in the same manner as the pri- mary tissues are engendered in the embryo, i. e. from a cellular substance. OF THE PRIMARY ORGANIZING PROCESS IN THE IMPREGNATED OVUM. § 117. It is not my intention to enter upon the consideration of the developement of the several or- gans of animals in this place ; this subject belongs to the Physiology. It is within my province, however, to describe the evolution and mode of formation of the various elementary parts and tissues that enter into the constitution of animal bodies. THE OVUM. 117 The Foetal Ovum. § 118. Soon after the appearance of the ovaries in the embryo of the human subject and mammalia, we observe preparations made for the production of new individuals. These preparations, indeed, only come into play at a much later period, viz. when manhood or the adult age is attained ; but, at the earliest period, eggs are discovered included in that which was hut just an egg, and these in their turn are endowed in perpetuity with the wonderful heritage of evolving their like. When the investing membrane of the extremely delicate ovaries of young embryos is torn through by means of a couple of pairs of fine forceps, and their contents, after being carefully divided into pieces, are mixed with a solution of sugar or a neutral salt and brought into the field of the microscope, numbers of extremely delicate trans- parent vesicles are perceived. These are readily distinguished from the spongy substance of the ovary, which looks loose and full of cysts, and finely granular. The vesicles, on the contrary, are perceived as transparent bladders filled with a homogeneous fluid, which to chemical re-agents comports itself like albumen, and including a darker mass often visibly attached to the inner aspect of the walls of the vesicle, and appearing in the guise of a rounded spot with an indefinite outline. § 119* The cells of the ovary {fig. 28, a) in which these vesicles lie embedded, appear to he of equal sizes ; they are round, extremely pale, and 118 ORIGIN, ETC. OF ELEMENTS. generally include several nuclei ; they are connected by means of a serous fluid, or an extremely delicate intercellular substance, and cover tlie vesicles lying flat upon the glass plate in such a way that at first they seem as if they were included within these (r n tu\ a, a , a ). § 120. When we succeed, by means of motion in different directions, and the application of a delicate hair pencil, in freeing the easily destructible vesicle from the surrounding cysts, its rounded spot comes into view upon its middle or towards one of its edges, and the object presents itself in the guise of a cell, the nucleus not homogeneous. Whether this cell becomes the Graafian vesicle, which, in the adult, includes the ovum, or is the rudiment of the ovum itself, I do not venture to say ; for it stands as a simple cell in the same rank, as it were, with newly formed cells at large (Jig. 216). In all likelihood the primary cell is the representative of the ovum, which then forms the zona pellucida and Graafian follicle ; or the delicate vesicle is the albuminous envelope which Krause has indicated as the covering of the ovum in the ovary of adults.* This latter view would he in accordance with that of Schwann, t who regards the vesicular part as the primary cell. The Unimpregnated Ovum in the Adult. § 121. In older foetuses the several parts of the ovum may be demonstrated such as they present * Miiller’s “Archiv,” 1837. S. 27. t “ Mikroscopische Untersuchurlgen,” &c. Berlin, 1839. S. 48. THE OVUM. 119 themselves in the ovaries of adults. The substance of the ovary, which is now of firmer consistence, includes numerous cysts of various sizes, generally from the |dh to the ^th of a line in diameter, but in some animals much more ; as in the cow, where they are 1^ line in diameter. These cysts are generally globular in figure, and are provided with a proper indusium. They form the Graafian vesi- cles or Graafian follicles {fig. 27, ci), in which the Graafian ovula (c), surrounded by the cells of the follicular body (Z>), are contained. This is surrounded immediately by Krause’s membrane of the albumen, which is generally obvious in the ovum of the cow, but was not visible in the subject of the drawing {fig. 27) ; it had probably burst. Within this albuminous membrane, and surrounded by fluid albumen, the vitellus or yolk is suspended at perfect freedom. This -vitellus consists of two globular- shaped vesicles, the outer of which, the zona pel- lucida (c), is of considerable thickness, hut without manifest structure ; whilst the second, the proper vitelline membrane* (tZ), of extreme delicacy, looks like an epithelium of the former, and includes immediately the finely granular vitellary substance {e). The flat-shaped germinal vesicle {f) is generally found attached to the inner aspect of the vitelline membrane ; sometimes, however, it is met with free amidst the vitellary matter. The middle of the germinal vesicle is occupied by the germinal spot {g), a structure which bears the closest possible resemblance to the true pus-globule. * Vide Note under next paragraph, § 122. ORIGIN, ETC. OF ELEMENTS. 120 Origin of the Ovum. § 122. The ovum is formed either in accordance with the law of involution, so that the albuminous membrane with the included nucleus forms the parent cell, in which the nucleus, as secondary cell, is transformed into the zona pellucida and vitelline membrane (the latter, perchance, no more than a layer of albumen*), the contents of this secondary cell being the yolk, whose nucleus is the germinal vesicle, and whose nucleolus is the germinal spot ; just as the germinal vesicle, when the nucleolus of the germinal spot appears, must be regarded as constituting the innermost cell. Or, otherwise, the germinal spot is already present in the original albuminous cell, the nucleus of which it forms as cell-germ, and upon and around this the germinal vesicle is evolved as the secondary cell, according to the ordinary laws of organic developement. In all probability the germinal spot, as the cytoblast or organic germ, is the primary formation, from which the germinal vesicle is evolved in the usual way, the vitelline and albuminous membranes being subsequently produced around this. In either case, cell within cell is very obviously included in the Graafian vesicle *, and this, the albuminous mem- brane, the vitellary membrane, and the capsule of the germinal vesicle, are to be viewed as the mem- branes of so many cells ; the first of these being the Graafian vesicle with the ovum ; the second, the homogeneous albumen ovi with the vitellus ; the * On the formation of the ovum, vide the “ Elements of Phy- siology ” of Dr. Rud. Wagner, by R. Willis, M.D., p. 36, et seq. THE OVUM. 121 third, the vitellus with the germinal vesicle ; and the fourth, a homogeneous, and, according to Wag- ner, also an albuminous fluid, including the germinal spot. Nor is this all : the germinal spot is itself even as certainly a compound body, — a cytoblast or organic germ, which, supposing the germinal vesicle actually to disappear from the fecundated ovum, is evolved from the germinal membrane at the same spot. Earliest period of Developement in the Fecundated Ovum, and Origin of the Embryo in the In- cubated Egg. § 123. In all probability, the germinal vesicle is formed simultaneously with the Graafian follicle ; and the yolk-cells are only produced subsequently around the germinal vesicle. The yolk is at first very small, and its capsule embraces the germinal vesicle closely ; it, therefore, increases in an in- finitely greater ratio than the germinal vesicle. Cell- germs arise, which surround the germinal vesicle and prove the first rudiments of the germinal mem- brane ; at the same time other cell-germs appear, which are rapidly evolved into white cells — the vitel- line cells for the formation of the vitelline cavity. On the inner aspect of the growing vitellary mem- brane, with the exception of the spot which is occupied by the germinal vesicle and the rudiment of the germinal membrane, arise other yellow cells, apparently as products of the vitellary membrane, which constitute the proper vitellary matter. Whilst these cells are produced, the exudation from the 122 ORIGIN, ETC. OF ELEMENTS. inner aspect of the vitellary membrane continues ; there is a perpetual production of yellow-coloured cell-germs between the vitellary membrane and the mass of cell-germs already formed, until the growth of the yolk is complete. These yellow cell-germs, including one another in concentrically disposed layers, also include the first-formed white cells, which are in immediate contact with the rudi- mentary germinal membrane ; and, whilst the number and volume of these last increase, the middle point of the white central cells of the vitel- lary cavity recedes more and more from the ger- minal membrane and germinal vesicle, yet is ever in connexion with them : so that between the vitellary cavity and the proligerous disc there is at length a canal or passage of communication established.* At length the ovum quits the ovary and the ger- minal vesicle disappears. In its place we have then the disc-shaped germinal membrane produced, which by and by divides into two layers ; the outer being distinguished as the serous layer, and the inner, the mucous layer, whilst the space between them is spoken of as the vascular layer. From the serous layer are evolved the animal and external organs ; from the mucous layer arise the organic and internal parts ; from the vascular intermediate layer, as the name implies, the blood and vascular system are produced. The germinal membrane consists of globular cells with nuclei and granules ; it grows by the growth and increase in number of these cells. * See an excellent figure of the parts here described in Wagner’s “ Elements of Physiology,” by Willis, p. 84. THE OVUM. 123 In the eggs of fowls that have been incu- hated for about sixteen hours wre begin to per- ceive the separation into layers in the germinal membrane ; at the same time also we distinguish a difference in their constituent elementary cells : the cells of the outer serous lamina are highly trans- parent, and inclose a limpid fluid and single nuclei with nucleoli and a few granules, very much in the manner of connected epithelial cells. The inner lamina, in an abundant and softer intercellular sub- stance, includes cells with various globular dark nuclei and fine granules.* In the middle of the germinal membrane, betwixt its laminae, now in- creased in size by the apposition and growth of cells, arises the area pellucida, a transparent spot or space consisting of smaller cells and granules ; and here it is that the embryo is formed by the inver- sion of the middle portion of the germinal mem- brane, which has increased in thickness, and the separation of the edges of the same part. The embryo therefore, as well as all the parts about it, is formed exclusively of cells. In the middle in- cluded layer of the germinal membrane it is that the blood-vessels are engendered ; these partly expand in the vitellary cavity, and then begins the period of the nourishment of the embryo from the yolk ; but without reference to this, every rudiment of a new part, as also the growth and evolution of the parts already commenced, take place by the further pro- duction of cell-germs and cells, and of structures com- posed by these. In the interior of the rudiments of * See a fine figure of these cells in the work of Wagner just quoted, p. 212. 124 FORMATION OF PARTS FROM CELLS. the vascular system are evolved the red-coloured per- manent * cytoblasts, organic germs or blood-globules, the liquor sanguinis, &c. : in a word, the blood. The further developement of the different compound parts will be treated of at length in the immediately following histological portion of this work. FORMATION OF THE VARIOUS COMPOUND PARTS AND TISSUES FROM CELLS. § 124. Should my notions in regard to the transformation of vegetable albumen, under the assimilating and vitalising forces of plants, into a fluid gluten or general cytoblastema, be confirmed, we should have the same accordance in the assi- milation and chemical metamorphoses of assimilable matters in the animal and vegetable kingdom, which has already been shewn by Schwann to obtain in reference to their structure and mode of growth. The fluid gluten of plants would then correspond to the fluid fibrine of animals ; and it is not unin- teresting to observe that both of these matters are distinguished by their power to form granules. A * The word permanent here is to be taken in a restricted sense. It is not meant that the blood-globules themselves undergo no change : they are perpetually changing, being re- solved so as to pass into the elements probably of all the tissues; and such portions of these tissues as are not unfitted for the uses of the economy, when they come to be changed and renewed, are very probably associated again, and again formed into blood-globules. The blood-globules are only permanent as regards their form : as blood-globules, they are at the acme of their developement ; without solution and disintegration, without losing shape and consistence, they cannot become or pass into other tissues. FORMATION OF PARTS FROM CELLS. 125 parallel has already been drawn between the sap of the roots of vegetables and the chyle of animals, betwixt the circulating fluid or blood of animals and the sap of the trunk or stem, branches, and leaves of plants, but without any very particular investigation of the nature of the resemblance be- tween them. The united researches of physiolo- gists and chemists ought to resolve this problem, the more speedily now, as the majority of the latter have very recently shewn nothing like the old indisposition to grapple with the difficulties of organic chemistry. The mutability of organic elements no longer rebuts inquirers, and the advances which have lately been made in the organic have been no less signal than those which have long marked the cultivation of the inorganic branch of chemical science. Should the idea be confirmed that the blood of plants, like that of animals, contains peculiar corpuscles * as one of its essential elements, then will the physiology of vege- tables and of animals be equally advanced by re- searches in the one or in the other ; every new discovery in the one will be the herald of a cor- responding discovery in the other ; and the science of organic life will thus acquire a double impetus in its onward progress. The daily increase of our knowledge in regard to the analogies in the morpho- logical life of plants and animals gives every reason to believe that such will truly be found to be the case. At all events, the inquiries of Schleiden and * A very important acquisition for the doctrine of the ’pneumatic relations, or respiration of vegetables , of which so little is yet known. 126 FORMATION OF FARTS FROM CELLS. Schwann have opened up a new and yet untrodden field for investigation — a kind of continent in phy- siology, the existence of which was long suspected, though never demonstrated, but which now lies open to the physiologist and the chemist, with every promise of a most ample harvest as the reward of any pains they may bestow in cultivating its soil. § 125. Many particulars bearing upon organiza- tion and reorganization by means of evolved cells having now been mentioned, we may next proceed to examine more closely the special relations of the cells in the constitution of the various tissues of the human and animal body. Just as we see the same building material, after it is worked, put together and employed to the most varied ends, used to erect the most dissimilar fabrics, so do we observe cells in the animal body modelled and arranged, after a plan which is partly known, in the most various manners. The cell which is the product of the living cytohlast is, in fact, a material prepared beforehand, and available for the most varied purposes in the organic fabric. From the nearly passive constituent, which in many cases may he held as fulfilling its destiny merely by occupying space, to the organ by which man is fitted to approach his Maker, every part of the body has one common mode of origin, even as organisms of all kinds arise from single cells. In the progres- sively forming organism every care is taken that plastic matter, in adequate quantity and of proper quality, according to its wants, he furnished. Hidden life in the fluid, in the shapable, precedes DIFFERENT CONSTITUTIONS OF CELLS. 127 revealed life in the solid, in the shapen. Fat, albumen and fibrine, or assimilable, nutritive and plastic matter, form the three first distinguishable grades towards the capacity to assume determinate forms and shapes in man and animals ; after these follows the formation of cytoblasts, the universal elementary type of all compound constituent parts ; then come the formation of cells, the co-ordination of cells, and the metamorphosis of cells. Of the different Constitutions of Cells. § 126. In the same way as the germinal vesicle is connected with the inner aspect of the vitelline membrane, the cytoblast is generally seen as the cell-nucleus adhering to a point of the cell-capsule which has arisen upon it, and increased in size by the progressive accumulation of an included fluid. The cytoblast only appears in the middle of the cell — 1st. When it has been accidentally detached from its connexion with the inner aspect of the capsule, and this is an event that rarely happens. 2d. When the specifically heavier cytoblast, descend- ing through the fluid of the cell, sinks to the lowest point, — examined from above, it of course appears to occupy the middle of the cell. 3d. When the cell is flattened, in which case the cytoblast always lies more or less truly in the middle of the hemisphere of the cell-capsule, depressed into the shape of a disc. When in the course of microscopical observations on cells, the cytoblast or nucleus is observed very generally on the edge of the vesicle, in all likeli- hood globular cells of recent formation are in the 128 FORMATION OF PARTS FROM CELLS. field (figs. 216 and 227) ; conviction of the truth of which, or otherwise, may be obtained by moving the object, and shading the light on one side. If such young cells swing free amidst or upon a limpid medium, then the subjacent nuclei will he seen to swing something in the manner of a pendulum, when the object hearer is slightly shaken ; and those within the vesicles can be seen to move hither and thither across their diameter ; in general, too, the vesicle is smaller relatively to the nucleus, the younger the cell is. When the primarily fluid contents of the cell augment, or imbibe water by endosmose from surrounding media, then the vesicle increases proportionately ; but when the cell gives water to a surrounding medium by exosmose, then it shrinks, and, in some rare instances, becomes irre- gular and wrinkled : generally it becomes flattened, the point of the vesicle opposite to that at which the nucleus is attached approaching this, and the cell passing through the changes of form which are shewn in figs. 227 and 228, a-f. § 127. From the fluid contents of cells, albu- minous granules are frequently precipitated, which, when they are very minute, and not in too great numbers, generally exhibit lively molecular move- ments. Should the cell lose its water after a copious precipitation of albumen, it appears granular, and may be confounded with the aggregation-corpuscle (§ 35) ; hut in general only the older, flat and detached cells, are properly granular {fig- 220). § 128. Occasionally the cell-capsule bursts and disappears, leaving the nucleus behind ; more com- monly, and in the horny tissues regularly, the DIFFERENT CONSTITUTIONS OF CELLS. 129 nucleus disappears, and then the flattened cell be- comes a scale or lamella {figs. 34 and 41) ; when this happens in the globular cell, then the vesicle is produced {figs. 208 and 209). Cell-nuclei are fre- quently granular, those of the cells of cartilage and of cellular fibres are so commonly. Under what cir- cumstances the nucleus and the nucleolus increase, whilst in the old nucleolus a new one arises, by which the nucleus becomes a cell, and also how the contrary of all this occurs, must be determined by future inquiries. The nucleolus, too, occasionally, perhaps more commonly than is imagined, is gra- nular ; this is the case regularly in the ganglionic cell {fig. 89j 2, 3), and in the ovum, if the germi- nal spot be taken as the indication of the cell- nucleolus. § 129. Cells vary in size according to the degree of their developement, according to their destina- tion, &c. ; they are seen of all dimensions, between that of the lymph-granule and the 60th of a Paris line ; in the ovum they are a Paris line and more in diameter ; next to the ovum they are largest in the cellular cartilages {fig. 57), and in those parts of the bones where the nuclei (the bone corpuscles) lie very much isolated {fig. 68 at a). § 130. The form presented by cells is also very various ; those that are isolated are generally spherical {figs. 21 6 and 227, «), ellipsoidal, egg- shaped, pear-shaped {figs. 217 an(l 89, 2, 4, 6), more rarely kidney-shaped or flattened. When many cells are closely crowded together they become polyhedral ; those only that are connected into a membrane, and whose form is flattened or lenticu- K 130 FORMATION OF PARTS FROM CELLS. lar, those of the cuticle, for example, are polygonal on their edges ; generally they are six-sided (figs. 21 5 and 226). Rounded cells heaped together always become flattened at the points of contact, just as we see soap-bubbles when they touch one another ( fig. 7% b) ; but when the cells, whether piled together or connected into a membrane, do not come into contact immediately, but are separated by an intercellular matter, then may they continue to pre- serve their original rounded figure, as is the case with the ganglionic cells ; or they may become poly- gonal or polyhedral, as we observe them in different epithelise (fig. 32, 2, 3 ; figs. 33, 47, and 214). § 131. When the cells pass into fibres, they become fusiform (§ 84 and 35), and in their linear connexion form cellular fibres, within which the nuclei are frequently to be observed connected by internuclear fibres (fig. 219, d~) ; these nuclear fibres perhaps even occur naked (fig. 203). When the cell becomes elongated, its vesicle then forms a rounded or pointed, but closed, tube at either end ; this, according to Schwann,* is the case in the crystal- line lens of the eye, and, according to Gurlt,+ in the acicular enamel of the pulp of the tooth. Should the cell only elongate in the form of a tube at one part, it acquires the shape of a club (Schwann, Tab. I. fig. 12). Cells undergo elongation in differ- ent directions, and form networks with one another, as is seen in the branched pigmentary cells (fig. 32, cl ; Schwann, Tab. II. fig. 9)- Cells increase * Mikroscop. Untersuch. &c. t Lehrbueh der verg. Phys. Tab. ii. Fig. 11. PIGMENT. 131 and are developed independently in the vicinity of the capillary vessels, apparently in consequence of endosmotic penetration of the surrounding cyto- blastema ; but how they are determined to assume such a variety of forms in the composition of the elementary tissues is unknown. Schwann* gives the following classification of the animal tissues, as the result of his inquiries in their present state : — 1st Class. — Isolated independent cells. To this class belong especially the cells of the various fluids,! — lymph-corpuscles, blood-corpuscles, mucus-corpuscles, pus-corpuscles, &c. 2d Class. — Independent cells united into con- tinuous tissues. To this class belong the whole of the horny tissues and the crystalline lens. 3d Class Cells, only the walls of which blend together : cartilage, bone, teeth. 4th Class Fibrous cells, or cell-fibres : cellu- lar tissue, sinewy tissue, elastic tissue. 5th Class. — Cells, the walls and cavities of which are alike blended or united : muscles, bones, capillary vessels. Pigment, Pigmentum nigrum . § 132. The substratum of the black pigment consists of minute granules, which, when isolated in a fluid, exhibit molecular motion by so much the „ * Op. cit. S. 74. f These we regard as cytoblasts, not as cells. 132 PIGMENT. more lively as the fluid is volatile,* and which, heaped together, absorb or reflect the rays of light in such a way that the mass, whether viewed by transmitted or direct light, appears of a black-brown colour. The several rounded granules, under a high magnifying power, appear pretty evenly dispersed through a hyaline substance ; individually, they are not black and opaque, but transparent {fig- 39, b, c, d). The pigmentary granules, as we observe them in the diffluent pigmentary matter of the choroid coat, form aggregation-corpuscles (pigment- ary corpuscles), which are less transparent than the mucus and cyst-corpuscle {fig- 32, 1, d), or they are inclosed in cells, to which they give their black colour. These pigmentary cells are met with either more isolated, or grouped together, as in the skin ; or they form membranes made up of polyhedral parts, as in the choroid coat of the eye {fig- 32, 2 — at a a, some cells are removed from the inter- cellular substance — 3, and fig. 33, upon the trans- lucent veins). As a general rule, the nucleus of the pigmentary cell appears clear and transparent, and it frequently includes a small darker nucleolus. Many pigmentary cells undergo elongation in dif- ferent directions into hollow fibres, which, meeting other pigmentary formations of the same kind, pro- duce a more or less perfect network of star-shaped cells. The nuclei of the multangular pigmentary * To obtain assurance that this is the case, let a small quantity of any finely granular matter, pigment, dust, any inso- luble precipitate, be added to water, oil of turpentine, alcohol, ether, &c., and let the vigour of the motions be compared with the volatility of the fluids successively employed. FAT. 133 cells disappear in horn {fig. 35, b). Pigmentary matter is met with in every part of a brownish-hlack or black colour. Fat Vesicles ; Fat Cells. § 133. In many parts of the human and animal body, a larger or smaller quantity of fat is very constantly met with. The quantity is generally in proportion to the degree of nutrition. The fat itself exists in the shape of small globular vesicles, and is generally intermixed with the cellular tissue. Col- lections of these vesicles are encountered particularly between and around the muscles of the eyeball, in the hollow of the orbit, between the muscles of the external ear in mammals, — situations in which they serve as pads or cushions, retaining parts in their relative situations, and aiding them in their actions. A quantity of fat, more or less, is also very regu- larly found upon the heart, covered immediately by the cardiac reflection of the pericardium, and around the great blood-vessels at their origins and termina- tions ; in the folds of the omentum and mesentery ; about the kidneys ; within the spinal canal between the periosteum and the dura mater ; in the cancelli of the short, and shafts of the long, bones ; in the subcutaneous cellular tissue, &c. The fat of the cellular tissue is obviously inclosed in membranous cell- vesicles, in which the nuclei are frequently to he discovered (fat cells). The ordinary fat vesicles measure from the Toolh to the Arth of a Paris line in diameter {fig. 31, b~) ; those of the spinal canal (a) are from the TToth to the Tooth of a Paris line 134 FAT. in dimensions ; when they are isolated or are im- bedded in a soft intercellular substance they retain their globular figure, but, like all other spherical cells, they become polyhedral when they lie in con- tact one with another, with no kind of interposed matter (Jig. 1% b')* The consistency of the fat included in the vesicles varies with the ratio be- tween the stearine and elain of which all fat con- sists ; it is very firm in the sheep, where the stea- * Although the majority of the fat vesicles are circular, a great number of them are of an oval form. The smaller are generally of the former shape, while many of the larger are frequently more or less elliptical. The magnitude of the vesicles is remarkably variable. A very common size is about ^A^th of an inch in diameter. In the fat vesicles of the omentum of a foetal calf I observed numberless gradations, from J^th to ■g^yth of an inch in diameter, although most of them were about •gT_tli of an inch. In the mesentery of a shrewmouse scarcely any fatty matter could be found, but some vesicles were observ- able, and these were so minute as to measure only from -g-^gth to g-jTy^th 0f an jneh. They were collected into small clusters. In the peritoneum of a young kitten the majority of the vesicles were about g-ipth of an inch, but some were only -^A^th. These latter occurred in clusters often not larger than the average sized vesicles. In the calf above mentioned the fat appeared to exist within the vesicles in a granular form, the granules being extremely minute, certainly not larger than 2"ooooth °f an inch in diameter; some of the large vesicles seemed to be only partially filled with this granular fat. The granules were best seen with a strong transmitted light. In the kitten I could not detect them. In the peritoneum of most young animals, as the fat is deposited in thin layers, the vesicles may be clearly distinguished with a Coddington lens, by extend- ing a bit of the membrane on a slip of glass and making the examination against the light. — G. G. HORNY TISSUES. 135 rine predominates, and is called suet, or tallow ; it is much softer in the hog, where the elain is most abundant, and where it is called lard. § 134. The soft fat of the solidungula is of a yellowish colour, and at 32° F. has a specific gravity of 0*914 ; it congeals at 48°, and at 90° it becomes fluid ; it contains about 37 per cent of stearine, and 96|- per cent elain. The fat of the hog is white, soft, and melts at a lower temperature ; it consists of about 38 per cent stearine, and 62 per cent elain. In the carnivora, the fat is soft, yellowish, and of a peculiar odour. In the dog it is composed of 17 per cent stearine and 73 per cent elain. The fat of the human infant is white, or of a pale citron yellow colour ; it is firm, and contains a large proportion of stearine. Fresh animal fat in general is dissolved and taken up by ether without any rupture of the containing vesicles. Fat defends and isolates the organs of the body, and, as a bad conductor of heat, it tends to preserve the temperature ; with abundant food it accumu- lates in the healthy body ; with indifferent and scanty supplies of food, and under the influence of disease, it disappears. Horn, and Horny Tissues. § 135. Chemically considered, horn comports itself like albumen, but it contains less azote than this substance. Horn forms the principal element in the outermost laminte of the animal body, viz. the cuticle and the various means for covering and protection, in the shape of nails, claws, hoofs, hair, 136 HORNY TISSUES. feathers, spines, scales, plates, &c. The horny substance is transparent, of a yellowish brown hue, hard, and elastic ; it softens without dissolving in boil- ing water ; it also softens when exposed to dry heat, and then melts and swells out. With dry distilla- tion it yields carbonate and cyanate of ammonia. Thrown upon an open fire, it burns, swelling up and diffusing a peculiar and well-known disagreeable odour. It is decomposed by concentrated acids and is dissolved by the caustic alkalis with evolu- tion of ammonia. Horn presents itself in the living body as a morbid product, and then frequently in the form of crystalline- looking rhomboidal tables ( fig. 172) ; at other times it appears as a congeries of dried cell-scales. The younger epidermic and epithelial cells exhibit the same chemical properties as fi brine. External Horny Indusice. — Epidermis, Epithe- lium, and Structures connected with them. § 136. All the surfaces of the body are covered with the cellulo-membranous layers which constitute the epidermis or epithelium. The epi- dermis, cuticle, or external covering, of the skin, consists of several layers of cells, which are pro- duced upon the corium, as a consequence of an un- interrupted process of exudation, accompanied by a like continuous formation of cytoblasts and cells. These cells incessantly produced below, are as in- cessantly thrown off by desquamation above. The most recently produced cells, which of course are those that are in contact with the corium, are like all young cells, spherical in their figure ; they he- EPIDERMIS. 137 come flattened in the same proportion as they approach the superficies : so that when examined on a section they are observed to undergo altera- tions of figure, from that of a globular cell provided with a nucleus, to that of a flat scale in which no trace of a nucleus appears {figs. 227 and 228 a,f). The innermost layers consequently form soft cel- lular membranes, the outermost layers constitute hard squamous membranes. The epidermis covers the entire external surface of the body, even the cornea of the eye {fig. 41). Rarely, perhaps never, do we find any intercellular matter, or matter in- terposed between the cells ; occasionally, however, a matter of this sort may be suspected in the seat of their formation, upon the surface of the corium, in the mucous layer of Malpighi. The epidermis is pierced at every point by the excretory ducts of the sebaceous and sweat-glands, and, with few exceptions, by the shafts of the hairs also. It always consists of layers by so much the more numerous as the part which it covers is more strongly compressed or constantly rubbed ; for example, in the palm of the hand and sole of the foot : among the mammalia it is in general by so much the more delicate the finer and thinner the hair is ; but wherever constant and strong friction is endured, the hair disappears, though there the excretory ducts of the cutaneous glands are very much developed {fig. 40, e, f). The hoofs, claws, talons, horns, nails, See., are not merely connected with the epidermis, but are in fact more strikingly developed portions of this tissue, just as the cutaneous glands and the hairs are invo- lutions of the same. 138 IIORNY TISSUES. § 137* The different tints of colour presented by the common integument depend on the pigment- ary matter which enters into its composition ; where this is wanting, the epidermis is transparent and colourless, or but very slightly tinged with the portion of pigment which is present in the sebaceous glands and Malpighian body. It is only in the negro that the cells of the cuticle sometimes present themselves with a pretty strong resemblance to the pigmentary cells. The Sebaceous Glands, the Sweat Glands. § 138. These organs are formed from involutions of the cuticle, and when their relation to this tissue is considered, they might be named inserted horny structures. We shall speak of the larger glands which are formed in the same way as the sebaceous and sudoriparous glands, such as the mammary glands, in the section which treats particularly of the secreting glands. § 139. Sebaceous Glands. — All the true glands having excretory ducts, stand in relation either with the epidermis or with the epithelium ; or, in other words, they are inversions or involutions of the cuticle or epithelium contained within the substance of the skin or mucous membranes, or penetrating beyond them. These glands severally secrete a peculiar fluid, different from the general circulating fluid, and which are referable to three grand classes — the fatty, the watery, and the mixed. § 140. The glands of the external integument are true secreting glands, which, in the simplicity of their structure, nevertheless agree essentially with SEBACEOUS GLANDS, 139 all others of a more complex organisation. The sebaceous glands are either proper in all their parts, or their ducts serve the double office of excretory canals and sheaths for hairs. In the most simple forms they present themselves as club-shaped crypts, which arise on the outer aspect of the common integument as funnel-shaped involved processes of the epidermis, and lie at greater or less depths in the corium. They secrete an unctuous or buty- raceous matter, — the sebaceous matter, which con- tains crystals of stearine ( fig . 31, cl), oil-globules (e), and pigmentary granules. The origin and developement of the sebaceous glands in the palm of the human foetus is represented in Jig. 239- At a the epidermis is seen, in the first instance, hemi- spherically depressed into the substance of the sub- jacent corium ; at f the gland is nearly fully formed, and the racemiform glandlets are evolved ; the spirally twisted or corkscrew-like excretory duct of the gland, f lies in the substance of the thick corium (see, also, Jig. 40, g, h, i). In the hide of the horse, also, the sebaceous glands are commonly moriform or botryoidal, from one-tenth to one quarter of a line in diameter ; on the scro- tum they occur unaccompanied by hairs (fig. 44) ; it is betwixt the semicircular elevations of the cutis, a, that the infundibuliform orifices, b, of the delicate common excretory ducts, c, are encountered ; these common ducts generally divide into two branches, d, which lead to the same number of particular mori- form secreting glands, e. The sebaceous matter is of a brown colour, and contains many pigmentary granules. In the skin of 140 HORNY TISSUES. the labia of the mare {fig. 45), the glands are more extensively developed ; the individual glandular vesi- cles (e) proceed to distinct and wide pedicles (o?), and there end and unite in the common excement duct (c), which is at the same time the sheath of the hair (J"). The sebaceous matter is of the kind just indicated. In the prepuce of the stallion (fig. 43), the several parts are still farther deve- loped ; the cuticle a is reflected inwards at b in the shape of a funnel, and forms the sheath of the hair and the common excretory duct c, into which the efferent canals fifi of the elementary glandules e, pour their contents. At d the sheath of the hair is seen forming or rather surrounding the bulb of the hair ; k is the excretory duct of the sudoriparous gland i, which lies imbedded among the subcutane- ous cellular tissue. The sebaceous matter often collects between the folds of the prepuce in large masses of a dirty grey colour, which possess varying degrees of consistency, from that of soft tallow to that of wax, and are soluble, hut not so readily as ordinary fat, in ether and boiling alcohol, leaving a residue of albumen and certain saline matters. In the hog the sebaceous glands are sacculated, and either unilocular, bilocular, or multilocular (figs. 160, l6l). The smallest vesicles are from the A A w tl 1 to the ¥^th, and the excretory canals are about the -J_th of a Paris line in diameter. On the snout we observe certain remarkable tactile organs which may be mentioned here, inasmuch as they also secrete sebaceous matter. The organs in question are tactile sacs very copiously supplied with nerves, and having a small bristle traversing their SEBACEOUS GLANDS. 141 centre ; they are about -i-th of a Paris line in length and about Thth in breadth, fusiform, and with thick parietes. They open upon the surface of the com- mon integument in a compound rosette -shaped nervous papilla {Jig. 101) ; they contain sebaceous matter in their interior, and in the middle a bristle, as said, growing from a bulb, about iTs-th of a line in thickness, conically pointed, inclosed in a regular sheath, and projecting about ^th of a line beyond the papilla. The sac is inclosed by the nervous bundle which forms the papilla. Other nervous bundles, which lie parallel with the skin, pass in multitudes across the interspaces, and there form abundant reticulations. The sebaceous glands of the meatus auditorius and of the inner skin of the external ear are greatly developed, and secrete the cerumen or wax of the ear, — a bitter, yellowish-brown, fatty matter. The sebaceous glands are absent in those situations where the skin secretes a mucous fluid, as the nose of the carnivora, the muzzle of the ox, the snout of the hog, &c. § 141. The sebaceous matter serves to anoint and preserve the scarf-skin, the hair, horn, &c. soft and pliant ; it also serves to a certain extent as a defence against external chemical and mechanical agencies, and has some influence upon the colour of the skin. In the time of heat, especially among female animals, it is poured out in greater quantity and of a stronger odour than at other seasons. § 142. In some of our domestic, and in several other animals, we observe small sacculated cavities formed by reflections of the skin in certain places, 142 HORNY TISSUES. in the walls of which the sebaceous glands are more largely developed and much more active than in the surrounding portions of integument. Such are the lachrymal cavities, as they are called, under the eye of the deer, the cavities between the hoofs of the bisulcate ruminants generally and the small sebaceous sacs near the udder of the ewe, the um- bilical sac of the common boar, the anal sacs of the carnivora, and the sacs which are found close to the glans clitoridis, especially in the Solidungula. § 143. The largest of all the sebaceous glands of the skin are encountered in the eyelids, between the marginal crescentic cartilages and the fibres of the orbicular muscle. These glands, which are universally designated by the epithet Meibomian , secrete a thin sebaceous matter, which is continually poured out upon the edges of the eyelids and around the roots of the eyelashes by the little openings which may be observed arranged in an even row behind the cuke. This thin unctuous fluid defends the edges of the eyelids from the moisture and acrimony of the tears, and also serves to prevent the escape of the tears at all times over the cheeks. The Meibomian glands are generally of a white colour ; but they are of very different forms and sizes in different animals. In all essential particulars their structure is that of glands in general, — they are divided into glomeruli, and these again consist of pediculated primary vesicles. In fig. 138 may be found representations of two Meibomian glands from the foetal calf of four months : numerous secret- ing vesicles c form acervuli or glomeruli, in the midst of which run the primary excretory ducts, SUDORIPAROUS GLANDS. 143 which all terminate in the common duct a, that ex- tends through the middle of the gland to open at b on the inner edge of the eyelid. In the horse the Meibomian glands are scarcely the length of small barley-corns. In man they extend over the greater part of the surface of the eyelid, and are readily seen, as among the mammalia generally, through the conjunctiva. As these glands open in the line of transition between the cuticle of the eyelid and the epithelium of the conjunctiva, they may be viewed as transition forms from the proper sebaceous to the proper mucous gland. § 144. Sudoriparous Glands. — These are among the number of recent anatomical discoveries. They have been particularly examined and described by Gurlt* in his investigations into the structure of the skin and its dependencies. The sweat glands may he said to be contained in the substance of the corium ; for the most part, however, they project into the subcutaneous cellular tissue, or they are even situated in it entirely, so that the corium is only transpierced by their excretory ducts. It is probable, though not yet demonstrated, that the sweat, like the sebaceous, glands are developed by inflections of the epidermis. They are generally larger than the sebaceous glands, and consist either of a congeries of sacculi, so that they appear of an irregular mul- berry form {fig. 43, i), which is their figure in man and the domestic mammalia generally, or they are simple sacs, which is the appearance they present * “ Magazin fur die gesammte Tliierheilkunde,” Bd. i. S. 194, Taf. II. III.; und Miiller’s “ Archiv.” 1835. 144 HORNY TISSUES. in the ox and in the carnivora. Their contents being watery and uncoloured with pigmentary mat- ter, they are highly transparent, and much more difficult to discover and to examine under the micro- scope than the sebaceous glands. Their excretory ducts, generally of extreme delicacy, and more frequently straight than sinuous or spirally twisted ( Jig. 43, &), either accompany the sebaceous ducts and open close to them on the surface, or they run and also terminate between these. The office of these glands, as their name implies, is to secrete the sweat. The insensible perspiration, however, is in all probability an exhalation of water and other volatile matters from the corium, — products of the blood which circulates in the peripheral capillaries covered only by the epidermis.* Horny Tissues connected with the Epidermis. § 145. Hair, t — Hairs are epidermic threads implanted in the substance of the corium, or they are horny cylinders produced by involuted and * There seems no occasion to deny the insensible perspira- tion as a product of the sudoriparous glands, as well as the sensible perspiration or sweat. The impermeability of the cuticle opposes an insurmountable obstacle to any escape of vapour from the surface, save through the pore of a sebaceous or sudoriparous gland. Something is indeed due to simple evaporation, but it has been estimated at no more than one-sixth part of the entire loss by the skin. — G. G. + Gurlt und Hertwig, “ Magazin fur die gesammte Thier- heilk.” 1836. Heft. ii. S. 201 ; und Muller’s “Archiv.” fur 1836. The hair-bulbs are described and figured by Gurlt in his ex- cellent papers, as closed, and it is only in this particular that my observations differ from his. HAIR. 145 revoluted processes of the epidermis. They stand in the same relation to the skin as the nails of man and the claws of animals, and, to a certain extent also, as the teeth to the gums that surround them. When a piece of the hide of an animal covered with hair, such as that of the ox or horse, or the scalp of the human subject, which has lain for about forty hours in a solution of carbonate of potash, is divided perpendicularly, and in the direction of the hairs with a very sharp knife, we frequently succeed in cut- ting through one or more of the hair-bulbs exactly in the middle. To obtain the best view of this object, a moderate or medium power should be employed, and it may be viewed either as an opaque body by direct light, or, a delicate slice being removed with an appropriate double knife, it may be examined by transmitted light. When the hair of the bulb divided in this manner is young, the appearance obtained is that which is represented in fig. 42. The epidermis b, of the cutis a, a, is reflected funnel-wise at c', and forms the particular excretory canals d, d, which unite in the common duct c of the sebaceous glands n, o, p, and also the sheath of the hair, penetrating for this end more deeply into the corium, and expanding at e in order to form the sheath of the hair-bulb ; it then contracts at f and being reflected at g, it again swells out and forms the proper capsule of the hair-bulb at h, receiving by the infundibuliform inlet below, the vessels i, and the nervous bundles c {fig. 94), which pene- trate to the pulp k ; the reflected epidermis then forms the shaft of the hair /, and this advancing clears the skin and appears externally at m. Should L 146 HORNY TISSUES. the root of the hair not be divided precisely in the line of its axis, or should the hair be old, then the appearances presented are those exhibited in Jig. 43, where the bulb and the secreting pulp are seen to be closed. In this way each hair is found to be, in fact, a horny tube, an immediate process of the epidermis, including what may be called a medullary central thread, produced in the substance of the corium or in the subcutaneous cellular tissue. The hair-bulb itself is nothing more than the deepest, latest formed, soft, and therefore expanded portion of the shaft, which, as it advances, hardens and contracts to the diameter of the shaft. At f, g, where the sac suffers reflection outwards in order to constitute the bulb, circles of cells are formed which harden, and being pushed onwards by others of more recent formation, continue adhering to the hair to its extremity. In some animals the hair appears articulated, which is a consequence of the circle of cells f, g, being produced alternately of greater and smaller sizes ; in other creatures the hair is secreted of different colours in different parts of its length, which is the effect of the ring of cells containing a larger or smaller proportion of colour- ing matter. The entrance to the medulla or pulp of the root ,ff is wide in young hairs, and vessels and nerves of considerable size are seen entering, and forming terminal loops at k ; but in old hairs, just as in old and fully formed teeth, the canal of access is very small, and in grey hairs it is almost completely closed. The use of hair or fur is obvious : by entan- gling a large quantity of air it becomes one of the HAIR. 147 worst conductors of heat, and assists animals con- sequently to maintain their temperature at or near the proper standard. The elasticity of the hairy coat of animals makes it a defence to a certain extent against mechanical injuries; and its unctu- ousness enables it to resist some chemical agencies. The whiskers or strong hairs about the muzzles of certain animals, particularly the cat tribe, are also in some sort especial organs of touch, and on this account deserve particular notice. § 146. Tactile Hairs. — The stronger the hair the deeper does it penetrate the corium. The roots of the whiskers, or tactile and peculiarly sensitive hairs of mammalia, observed about the lips and round the eyes, lie completely under the skin, sunk amidst the cellular tissue, and sometimes even the subjacent muscles. The bulbs of these hairs are enclosed within a strong, highly vascular fibrous covering which is identical in its structure with the tactile sacs of the hog’s snout (§ 140), being sur- rounded by a hollow nervous bundle which forms a circle of closed terminal loops immediately under the epidermis about the orifice of the sheath for the hair. Into the central pulp of these great hairs we also observe an abundance of nerves surrounded by blood-vessels entering, the terminal loopings of which, in all probability, are the same as those observed in the roots of the large bristles of the hog.* * The peripheral distribution of the cutaneous nerves is best observed by achromatic glasses in the skin of the hog after it has been boiled and laid in oil of turpentine. An injection of the vessels with levigated cinnabar or white lead suspended in 148 HORNY TISSUES. § 147. Wool. — Wool is a kind of hair familiarly known, which differs from the ordinary hairs of such animals as the horse, ox, dog, &c. in its greater length, and in being crisped or curled in various degrees. Wool also differs from the hairs of the animals mentioned in being not cylindrical like them but irregularly flat.* The hairy coats which are characterised as far are also modifica- tions of the same structure which it is sufficient to mention. § 148. Bristles. — These, too, are but stronger hairs. The bristles of the hog grow together in threes, in more or less completely closed cavities filled with fat cells (figs. 71, 7^, and fig. 94). The outer ends of hogs’ bristles are generally seen split into two or three. The extremities of hairs are usually simple and solid.t Horny Defences. § 149. The extreme parts of man and the mam- malia are terminated and protected more or less completely by nails, hoofs, &c. These defences are principally developed in the course of the second oil of turpentine, brings these into view. The primary nervous fibres accompany the terminal loopings of the capillary vessels. The double knife is of essential service here. This instrument consists of two lancet blades, the edges of which can be approxi- mated in various degrees and fastened whilst sections are made. * Some interesting illustrations of the structure of hair and v/ool are given in Martin’s “ Natural History of Quadrupeds,” p. 156, from observations made by Mr. Youet. — G. G. f The work of Eble, “ Die Lebre Von den Haaren,” 2 Bde., Wien, 1831, is extremely full upon all matters connected with the hair. NAILS. 149 half of the intrauterine life. They consist, in the first instance, of a congeries of polyhedral nucleated cells without intercellular matter {fig. 2*26), and are soft and yielding. At the period of birth, indeed, they are still soft and fibrous ; but they soon harden when exposed to the air, the nuclei and nucleoli of the horny cells disappearing at the same time {fig. 34). When these horny tissues are coloured, pigmentary cells in variable numbers but disposed with a certain degree of regularity, are always readily discovered. During the foetal period these pigmentary cells are seen to be provided with nuclei and nucleoli ; in the horny parts of older animals, though the pigmentary cells are still readily enough demonstrated and sharply defined, they are without nuclei {fig. 3,5, b, b ; fig. 38, cl, dfi The nails of man, the claws of carnivorous animals, and the hoofs of the pachydermata, ruminantia, and solidungula, serve as means of defence against mechanical injury, and in many cases as weapons of offence. They may be viewed in every case as a multilamellar, peculiarly hard epidermis, furnished with a core, — a highly vascular and sensitive por- tion of the corium very commonly stretched over some terminal bone. The only exception to this is in the appendages called corns in the horse, which include no bone or bony process. Implanted, Flat Horny Structures. § 1.50. Nails of Man. — The nails lie with their canalicular hollowed out surfaces upon the vaulted dorsums of the last articulations of the toes and 150 HORNY TISSUES. fingers, and are attached by means of mutually pene- trating ridges of the horny structure and the corium. The posterior and wedge-like ends or roots of the nails are inclosed between duplicatures of the corium about two lines in depth ; and it is in this situation that we observe numerous filiform papillae sunk in the edge of the root, precisely in the same manner as single papillae are seen to penetrate the roots of the several hairs. These papillae are the sources of growth of the nails, just as the papillae are the sources of growth of the hair. This accordance in struc- ture between nails and hair is further manifest upon the convex aspect of a nail, with this difference however, that as there is no sebaceous matter poured out into the sheath of the nail, the sheath often remains adherent to the surface of the nail. As it is obvious that the longitudinally disposed connect- ing ridges of the corium remain stationary, whilst those upon the corresponding surface of the nail are in a perpetual state of progression, it would he difficult to conceive how the connexion between the nail and corium could be maintained, were it not that the entire living surface in contact with the nail was a secreting matrix and perpetually elaborat- ing horny cells, which are added to those prepared by the papillae at the root of the nail, and so strengthen it continually from the root onwards to the point where it becomes free. § 151. The nail in the human foetus, whilst yet soft and in the first period of its evolution, consists of nucleated cells, the youngest of which lie at every point of contact upon the corium. Even in adults young cells are always to be discovered at CLAWS HOOFS. 151 the edge of the root, which become horny outwards in successive layers. § 152. Claws of the Carnivora. — These only differ from the nails of man and the quadrumanous mammals in this, that they almost entirely surround the last digital phalanges, being completed on the plantar aspects by a longitudinal streak of cuticle. These claws are either colourless or coloured. When they are coloured, many fine pigmentary cells are observed forming streaks in the anterior vaulted portions, precisely as in hoofs that are streaked (fig. 35, b, b ). The root of the claw in the dog is surrounded by a projecting edge of the nail-sup- porting digital phalanx. The same segments of the paw in the cat, tiger, lion, See,., are drawn so much backwards and upwards that in ordinary pro- gression the points of the claws do not come into contact with the ground, an arrangement by which they are never blunted, and so made useless as in- struments of prehension, when at the will of the animal they are brought into play. In the dog, where there is no arrangement of this kind, the claws are always found blunted and worn away. The use of the claws as means of defence and of offence is obvious. Horny Capsules. § 153. Hoofs of the Ruminants. — These are greatly strengthened but still immediate continua- tions of the cuticle as it passes over the last digital phalanges of the extremities. The particular parts of the hoof of an ox, sheep, or deer enumerated 152 HORNY TISSUES. are, 1st, the crust or wall, which, as the part corre- sponding to the nail or claw, surrounds the anterior and lateral aspects of the last phalanx ; and 2d, the sole, which protects the plantar aspect of the same hone. The soft parts that lie between the bony digit and the hoof are, as in the human sub- ject, a continuation of the corium, with the hoof for its cuticle. The hoof and this portion of the corium are in most intimate connexion, the fusion being effected by the same arrangement of parts as that which we have already seen to exist between the nail and the piece of integument that supports it in the human subject. The softer fleshy parts lying between the bone and the hoof are to he regarded as a continuation of the corium with the horny hoof for its cuticle. Where the hoof lies perpendicularly upon or over the corium the union takes place by the mutual reception of perpendicularly arranged horny plates from the hoof and of fleshy lamellae from the corium. But in situations where the hoof is the substratum and supports the soft parts, the con- nexion is of a different kind, and takes place by means of numerous fusiform papillae containing an abundance of vessels and nerves, and received into funnel-shaped pits of the interior or upper aspect of the hoof. This mode of connexion is observed at every part where the growth of the hoof is most active, — the growth taking place as usual by the evolution of new cells from the surface of the matrix ; it consequently obtains all around the upper edge of the hoof, which as corresponding in the form and arrangement of its parts to the root of the human HOOFS. 1 53 nail, may be spoken of as the root of the hoof.* The place where the horny wall of the hoof begins is indicated externally by a slightly raised line, along which there is a sudden and marked increase of the production of the horny epidermic cells. The wall of the hoof is pierced from the crown to the bearing edge by many fine canals, and when coloured it is marked by pigmentary striae. The canals belong to the sebaceous follicles ; the coloured striae are due to intermingled pigmentary cells. § 154. Hoofs of the Hog The true hoofs of the hog are formed of fine compact horn ; they are the same in all respects as those of the ruminant. The false hoofs of the hog are less completely de- veloped, and, in point of structure, hold a middle place between the true and the false hoofs of rumi- nants. In the walls of the true hoof especially we observe papillae running diagonally downwards and outwards from the upper edge, and continuous with corresponding delicate tubuli which end on the outer surface of the wall. § 155. Hoof of the Horse. — The hoof of the solidungule presents us with the structure and pecu- liarities of the horny casings in the highest per- fection.! * The arrangement of parts is seen in the representation of the hoof of the horse, Jig. 36, b; and in the nail of man ,fig. 40, c, d. + To examine the structure of the horny tissue microscopi- cally, it is essential to be provided with fine laminae cut in different directions and from different parts of the structure to be investigated. The black-brown or streaked hoof of a horse, for instance, should be cut perpendicularly through with a fine saw, and then slices taken from different parts, — perpendicularly, transversely, slanting in various directions, &c. The surface of 1,54 I-IORNY TISSUES. In a section cut perpendicularly from the posterior wall {fig. 36), we observe on the crown edge a the conical and spindle-shaped papillae b, continued onwards as fine canals, and between these, excretory ducts of glands, which enlarge opposite the places where the papillae contract to a point, and then turn spirally round like the ducts of the sebaceous glands, becoming narrower in their course through the horny parietes, where the spiral turns are also less regular. In the anterior or digital wall of the hoof the papillae pass over into horny infundibula and canals, which are at the same time the ducts of the sebaceous glands. These filiform and twisted canals are rather finer than human hairs ; they run parallel to one another downwards through the wall {fig. 37, a), and open on the inferior or bearing edge of the same part, as the section represented in fig. 38 shews.* The canals contain sebaceous matter, which in black hoofs is of a brownish-black colour, and, therefore, contains numerous pigmentary gra- nules. Other parts of the hoof contain precisely similar canals. The horn of the sole and frog of the hoof is soft and elastic in a very high degree. these slices having been made smooth with a tile are to be glued to a strong board, and, when firm, reduced by planing. The larger and cleaner shavings from each section are to be collected separately, and the planing continued till the pieces are re- duced sufficiently. These are then to be detached by means of warm water, dried, and having been dipped in oil of turpen- tine, are fit for examination. The shavings are to be treated in the same way. 3 Vide Explanation of the Plates, Jiffs. 36-39. HORNS. 155 The substance of the hard masses called corns, which are seen on the inner aspects of the legs under the carpus in the fore legs, and under the ankle joint or tarsus of the hind legs in the horse, is also soft in its texture. It bears the same relation to the corium as the sole of the hoof does to the portion of integument wdiich it protects. § 156. Horns of the Ox, Sheep, fyc. — These horny capsules have very much the same structure as the walls of the hoof in the same class of animals, as also in the pachydermata and solidungula. The conical process of the frontal bone which supports the horn (the core of the horn) is somewhat rough on the surface, and is marked by numerous more or less longitudinal furrows in which run the vessels of the superimposed layer of corium, just as wre observe them in the coffin bones of the horse or ox. At the root of the horn the cuticle is greatly strengthened, precisely as it is along the crowm edge of the hoof, and from this circle onwards the horn is continually receiving accessions of new horn-cells in the way we have already seen to pass, when speaking of the growdh of nails, claws, and hoofs, these cells being produced at every point upon the surface of the soft parts covering the core, and the horn being gradually pushed on by their accumula- tion from the base towards the point. The bony core is not generally more than about two-thirds of the length of the horn ; but from the point of the core certain vessels proceed which run through the axis of the solid part of the horn, and only terminate at its extremity. The walls of the hollow portion of the horn consist of concentric and severally in- 156 HORNY TISSUES. eluding laminae, with longitudinally disposed ridges and intervening furrows, so that on the surface of a transverse section the horny laminae present them- selves as concentric sinuous lines. Immediately upon the corium of the core newly formed horn-cells are found in abundance, which in dark-coloured horn are intermixed with the pigmentary matter of the Malpighian or mucous hody. Delicate sec- tions of compact horn exhibit the elementary layers {fig- 34, A), which in fibrous horn are lineally arranged, and more firmly connected lengthwise than laterally (B). In the longitudinal section of the massive point of a horn the central vessels or canals are observed in the axis or middle {fig- 35, c, c), and in streaked horn, angular and polyhedral corneous pigmentary cells arranged in longitudinal lines, exactly as in streaked nails, claws, and hoofs {b, b, b). The sebaceous glands of horns are still less known than those of hoofs ; it is very seldom, indeed, that we discover a trace of their excretory ducts, which as well as the glands must nevertheless exist, as sebaceous matter is a kind of necessary adjunct to the epidermic tissue in all its modifi- cations. COVERINGS OF THE INTERNAL SURFACES OF THE BODY EPITHELIA. § 157- Recent investigations have shewn that not the skin only hut all the naturally free surfaces of the human and animal body are covered with cuticles which, in the interior of the body, are called epithelia. The epithelia are always in contact with fluids, and are, therefore, of a soft and pliant EPITHELIA. 157 nature ; the nuclei of their cells do not disappear like those of the cells of horn. Like the epidermis, the epithelia are engendered on the free surfaces of internal membranes by a regular exudation of cells, which compose them in their continuity, and scale off in quantities proportioned to the amount of ex- ternal influence to which they are exposed, in a greater measure, consequently, from the mucous than from the serous membranes, from the mouth and intestinal canal than from the air-passages and the ducts of glands. The forms presented by the epithelial cells are very various. In the tessellate or pavimented epi- thelia, the cells are simple, lenticular, and attached by their flat sides. In the cylindrate epithelia, they are campanular, cylindrical, or in the form of short cell-fibres, and are either sessile or pediculated in their attachment. The free surface of the outer- most cells is in some parts covered with delicate movable processes (cilise), and the epithelia so furnished are entitled ciliate epithelia. § 158. Tessellate Epithelium. — This form of epithelium covers all the more delicate membranes of the internal surfaces of the body, viz. the finer mucous membranes that are without special glands, and the serous and synovial membranes. It is com- posed of lenticular cells, which are generally em- bedded in an intercellular substance, contain nucleo- lated nuclei in their interior, and form either a simple cellular membrane, or a membrane of but a few layers of cells. This form of epithelium seems to. exfoliate rarely. 158 HORNY TISSUES. § 159. Tessellate Epithelium of Serous Sur- faces : («). Of the Lymphatic and Sanguiferous Systems. — The larger blood and lymphatic vessels consist of a number of concentric laminae of divers formation severally enclosing one another. The outermost layers consist of cellular tissue ; the second or middle, of fibres or fibrils which confer on the vessels their passive or active contractility, — these are elastic tissue, contractile and muscular fibres ; the third, or innermost layer, is a serous membrane which extends into the most minute ramifications of the vessels, and can even be de- monstrated in the capillaries ; it is covered with a delicate tessellated epithelium which, although it is probably never absent, is nevertheless but rarely visible in the capillaries. The epithelium of the vascular system is more especially easy of demon- stration on the walls of the cavities of the heart and of the great vascular trunks, particularly of the venous system ; it is not so readily shewn in the arteries and absorbents ; in the capillaries it is, as just stated, of the greatest delicacy, and seldom re- cognisable. If the lenticular cells of this epithe- lium do not obviously inclose nucleolated nuclei,* as those of tessellated epithelia in general do, then must we view it as a cytoblast membrane, and not assent to Vogel’s t proposition, that the pus- globules alone are neither more nor less than altered • The appearance of tessellated epithelium is given as seen under a low power in Jiff. 47, under a higher power in Jiff. 226, and the individual cells are represented in Jiff. 193, a. t “ Untersuchungen liber Eiter und Eiterung,” &c. EPITHELIA. 159 epithelial cells, but presume the same of the lymph and blood-corpuscles themselves ; and this the rather from the epithelial cells of the vascular parietes being often scarcely larger than the blood-globules. In every case the detached cells of the vascular epithelium when mingled with blood-globules can only be distinguished from them with great difficulty and with particular attention, the marks of distinc- tion being especially their paler colour and the nucleoli which they contain. § 160. (5.) Tessellate Epithelium of the Serous and Synovial Sacs All the serous membranes of the internal cavities, the inner membranes of the lymphatics and blood-vessels inclusive, are provided with a tessellated epithelium, which only differs from that of the lining membrane of the heart and great vessels in having the cells of rather larger size. This is the form of epithelium that covers, 1st, the pleurse, — the pleura costalis, and the pleura pulmonalis ; 2d, the pericardium, both where it forms the bag that encloses the heart, and in its reflection over the surface of this organ by which it forms its external envelope ; 3d, the peritoneum — abdominale et viscerale ; 4th, the tunica vaginalis testis, both as it includes and covers the testis ; 5th, both aspects of the tunica arachnoidea of the brain and spinal cord ; 6th, the inner serous lamina of the dura mater of the brain and cord ; 7th, the outer surface of the pia mater with the exception of so much of it as lines the ventricles of the brain, which is furnished with a ciliary tessellated epithe- lium ; 8th, the membranes of the ovum ( fig . 103.) § 161. Tessellate Epithelium of Mucous Mem - 160 HORNY TISSUES. branes. — Every form of epithelium is encountered covering the mucous membranes. A tessellate epi- thelium covers the mucous membrane of the cavity of the tympanum and of the cells of the pars petrosa of the temporal bone, the mouth (fig. 220), and partially the fauces, the oesophagus, the stomach save where the oesophagus enters, the vesicuke seminales, the pelvis of the kidney (on this last as well as on the urinary bladder passing over into the cylinder epithelium) ; further, the nymphse, clitoris, vagina and its parts as high as the middle of the neck of the uterus ; the inner aspect of the sclerotic and cornea, and the outer aspect of the choroid of the eye ; still further, the most delicate secreting canals and vesicles, — the finest excretory ducts of the salivary glands, of the liver, of the larger mucous glands, and of the tubuli uriniferi. All the points of transition of the skin into mucous membrane possess a covering analogous to the tessellated epithelium ; for example, the lips, the outer aspect of the membrana tympani, and even the surface of the meatus auditorius ex- ternus, the entrance into the nostrils, the margins of the eyelids, the external orifice of the male ure- thra, and of the female pudenda generally. Upon the synovial membranes the tessellated epithelium forms several layers. The clear spines described by Valentin,* as occurring in the angles of the cells of the choroid plexus, are the cilise of its ciliate epithelial cells (fig. 221 and 222, c). The tessellate epithelium not unfrequently passes over into a couched fibro-cellular epithelium (fig. * Nov. Acad. Nat. Curios, p. 45, tab. iv. fig. 24. CILIARY EPITHELIUM. 161 102, c), for instance on synovial membranes and vessels ; it also sometimes encloses capsule - like papillae, for example, in the tongue. § 162. Ciliary Tessellate Epithelium. — The tessellated epithelium which covers the dehcate pia mater that lines the cerebral cavities, not even ex- cepting the infundibulum, the aqueduct of Sylvius, and the cavity of the olfactory nerve, supports an abundance of very active ciliae,* which are attached along the edges of the epithelial cells to little warty- looking elevations (_ fig . 221 and 222). Examined in front, the cells appear in the guise of B, fig. 48. The ciliae are filiform, and move in the manner of the lash of a whip. The cylinder ciliate epithe- lium of the air-passages acquires the form of the tessellated ciliate epithelium in the finer subdivi- sions of the bronchi. In the primary tubuli of nerves an active ciliary motion is conspicuous prior to the coagulation of their contents ; the motion seems to he produced by short conical ciliae t {fig. 88, 4, a, and 5). Should the interior of the nervous tubuli be really found to exhibit the ciliary phenomena, which have been suspected there, a ciliary tessellate epithelium will in all probability be discovered as their cause ; for ciliary organs have not yet been found connected with any other structure than an epithelium, t * Discovered by Purkinje, Muller's “ Arcliiv.” 1836. S. 289. f It is only with the best glasses and lamp-light that these ciliae are visible, a fact of which I have often satisfied myself in company with Professor Valentin, who first described them. X The contents of the nervous tubuli are obviously as fluid as the blood during life. Vide what is further said of the structure of nerve, § 262 et sequent. M 162 HORNY TISSUES. The cilise are in general, as upon the cylinder ciliate epithelium, directed towards the natural out- lets of the cavities or canals they occupy, and, there- fore, move the fluids with which they are in contact in this direction.* § 163. Cylinder Epithelium. — As the lenticular cells of the tessellate epithelium lie in the plane of the general epithelial surface, so do we find the elongated epithelial cylinders of the cylinder epi- thelium placed perpendicularly upon the plane they cover ; cylinder epithelia, indeed, are very com- monly attached either immediately or by the medium of a style, to a simple tessellate epithelium, from which the elongated cells seem to grow much in the same way as grain does from the ground {Jig. 46, b, c, in section). The form of the individual epithelial cylinders is very various, and this apparently according as they contain one or more nuclei lying one over another, or according to the number of cells of which they consist, and the length of these severally. When the tessellate epithelium is passing over into the cylinder form, the cells first stand more raised, or in the guise of hemispheres, from the surface ; then they rise still higher, and present themselves as semiellipsoids ; farther on, the base of the cell appears constricted, and the ovoid or amygdaloid epithelial body begins to be pediculated ; the style grows thinner and longer, and the corpuscle * An historical account of the discovery of the cilise, as well as many original observations, will be found in the admir- able article by Professor Sharpey, “ Cyclopcedia of Anatomy and Physiology,” vol. i. p. 606. — G. G. CILIARY EPITHELIUM. 163 becomes campanulate, and then cup-shaped. These transitions may be followed almost without a break upon the conjunctiva of the inner aspects of the eyelids (_ figs. 47 and 48) ; in the intestinal canal, and in the stomach at the cardiac orifice ; in the larger ducts of the salivary glands ; in the ductus choledochus communis ; in the prostate, Cowper’s glands, vesiculse seminales, vas deferens, and tubuli semeniferi, and in the urethra. The many-celled epithelial cylinders grow as the single- celled do from a level tessellate epithelium : after one cell has acquired the cup -shape, the sub- jacent lenticular tessellate cell begins to rise, being connected with the incident one by means of the common style, it is then pinched off from the newly formed tessellate cell and becomes fusiform ; the cell just formed undergoes the same process, and so on, until the compound corpuscle finally contains two, three, four, and it may be, five nuclei, and is thus produced into a kind of free cellular fibre {figs. 223 and 224). Cylinder epithelia, so far as I am aware, are only met with upon mucous mem- branes ; the multicellular present themselves par- ticularly in the nostrils, in the trachea, in the uterus, in the gall-bladder {Jig. 24), and fully de- veloped in particular parts only of the intestinal canal. § 164. Ciliated Cylinder Epithelium. — The crowm of the cup-shaped and many-celled epithelial cylinder of several of the mucous membranes is covered with cilise {fig. 48, A, figs. 223 and 224), which are broader and blunter at the point than 164 HORNY TISSUES. those of the ciliary tessellated epitlielia, Cylinder epithelia with cilia are found in the nasal cavities, frontal sinuses, maxillary antra, lachrymal ducts and sac, the inner angle of the conjunctiva, the posterior surface of the pendulous' velum of the palate and fauces, of the Eustachian tube, the larynx, the trachea and bronchi, to the finest divisions of these last, on the inner portions of the vagina, the uterus, and the Fallopian tubes. In the middle of the crown or circlet of cilia, the globular outer nucleus of the epithelial cor- puscle is observed. This nucleus projects like an hemisphere, and, under the compressor, or betwixt two glass plates, but also when no force has been used, frequently escapes from its nidus, and is then found at liberty (Jig. 48, C, C, A and B, e). In the ciliary cylinder, as in the ciliary tessel- lated epithelium, the motions of the cilia are directed towards the natural openings of the cavities or canals they cover : in the uterus, for instance, to- wards the os uteri ; in the larynx, towards the rima glottidis, &c. ; by this means the investing mucus is carried onwards, and finally expelled. The motions of the cilia seem to depend on minute, but very indistinctly visible muscles, which lie under the ciliary elevations of the crown of the corpuscle to which they are connected by one extremity. A surface covered with cilia in active operation, when viewed obliquely or in perspective, generally presents the appearance of a field of corn waving with the wind. The motions of the cilia severally are hook- like, whip-like, & c. The ciliary motion and the CILIARY EPITHELIUM. 165 cilise were first seen and described by Purkinje and Valentin* in man and the mammalia. § 165. Ciliary motions are far more general among the invertebrate than among the vertebrate series of animals. The invertebrata that live in water have even very commonly cilise on certain portions of their external surface ; and in the in- fusoria these delicate processes serve as means of locomotion ; in the pediculated vorticella {fig- 87), which presents so striking a resemblance to the bell-shaped and cup-shaped ciliary corpuscles, they serve as means of attracting nutriment. The crea- ture establishes circular currents in its vicinity by means of its cilia}, and so brings organic molecules or small infusoria within its reach, when it suddenly retracts the body upon the now spirally twisted pedicle and closes the campanular orifice (C). This motion of retraction, as I conceive, depends on the composition of the pedicle, which consists of a vessel, which the creature has the power of injecting with fluid, and so of erecting or straightening, and of a fine contractile bundle wound spirally about the vessel, by the contraction of which the vessel * Muller’s “Archiv.” 1834, S. 391 ; also in the tract entitled, “ De Phoenomeno generali et fundamentali,” &c. Vratislavise, 1835 ; and in a paper, “ Ueber die Unabhangigkeit der Flim- mer-bewegungen der Wirbelthiere von der Integritaet des cen- tralen Nerven-Systems,” in Muller’s “ Archiv.” 1835. The subject was still further pursued by Henle in his Inaug. Diss. “ Symbol* ad Anatomiam Villorum Intestinalium, imprimis eorum Epithelii,” &c. Berl. 1837 ; and “Ueber die Ansbreitung des Epitheliums in mensch. Koerper,” in Muller’s “ Archiv.” 166 HORNY TISSUES. is emptied and the retraction effected.* In this structure we have an instance of an apparatus of locomotion of the simplest kind, — the effect follow- ing- the antagonism of a single erectile canal and a single contractile bundle. Inversions or Invaginations of the Epithelium — Epithelial Glands. § 166. The mucous membranes being but pro- ductions of the general external integument over the open cavities of the body, and agreeing with the skin in structure in all essential respects, we might a priori have expected to find epithelial glands, or glands connected with the coverings of mucous mem- branes, just as we had found epidermal glands — sudoriparous and sebaceous glands — connected with the skin. And this we do in fact ; the mucous membranes are plentifully supplied with involutions of the epithelium endowed with the secreting faculty, and denominated mucus-glands in virtue of their office, which is to secrete the slimy fluid with which the mucous membranes are bedewed. They are commonly divided into mucous crypts, which are simple sacs, and mucous glands, which are con- stituted by a cluster of such crypts terminating in a common canal. The epithelium of the mucous membranes is * Looking at the representation of this creature in Ehren- berg’s masterly work, “ Die Infusions -Thierchen als Voll- kommne Organismen,” fol. Leipz, 1838, I conclude that either I am wrong in the views above stated, or that Ehrenberg has overlooked the purpose of the spiral bundle. MUCOUS FOLLICLES AND GLANDS. lG7 also to be understood as covering all the processes which these send off in the shape of ducts to glands of a larger size, and secreting peculiar and divers fluids — the liver, pancreas, &c. &c. As these canalicular processes, however, are formed by the mucous membrane at large, and not merely by its epithelial indusium, they will not be spoken of here, but under the head of the apparatus to which they are subordinate — the glands. § I67. Mucous Follicles These are vesicular, more or less completely pediculated, simple involu- tions of the epithelium into the subjacent corium. They are met with in all the mucous membranes which are habitually covered with a proper thick slime ; they are wanting, on the contrary, in those that are merely moistened with a watery or very thin fluid, such as the frontal and maxillary sinuses, the cavity of the tympanum, &c. These follicles secrete the mucus-corpuscles ( Jig . 25, B), which, mingled until serous fluid and detached epithelial cells or cylinders compose mucus. It is very neces- sary not to confound with these mucous follicles the larger involutions of the entire mucous membrane, and into which mucous follicles and mucous glands, or simple and multilocular inversions of the epi- thelium, pour their products. § 168. Mucous Glands These in point of structure and general appearance are almost identi- cal with the sebaceous glands of the skin. They lie deeper in the mucous membrane than the follicles, and frequently extend beyond this into the sub- mucous cellular tissue. They consist of agglo- merated glandular vesicles, which form botryoidal 168 HORNY TISSUES. masses, whereof two commonly lie near one another, and unite their several excretory ducts into one common to both, which then opens upon the sur- face.* Their office, like that of the follicles, is to secrete the mucus which, poured out upon the surface of the mucous membranes, lubicrates and defends them, aiding the transmission of the chyme and fteces through the alimentary tract, protect- ing the nose, the windpipe, and the bronchi from dust, &c. § 169. With a view to assigning to the epithe- lial glands their place in a natural arrangement of the glandular system, the following brief sketch of a division of its various elements is here subjoined: — Those organs only are to be regarded as true or secreting glands, which from the general cir- culating fluid separate a peculiar fluid, a process which is accomplished by one or more pediculated vessels or elongated canals, the separated fluid being mostly received into excretory ducts which terminate upon the external surface of the body or on the surface of a mucous membrane. They are con- veniently divided into 1st, Cutaneous Glands — inversions of the corium and of the mucous mem- branes; and, 2d. Cuticular Glands — inversions of the cuticle into or through the corium. The cutaneous glands again divide themselves into (a) glands of the skin, and (6) glands of the mucous membranes ; and the cuticular glands into ( a ) glands of the epidermis — epidermic glands, and ( b ) glands of the epithelium — epithelial glands. * Gurlt, vergleichende Pliysiologie, Taf. m.Jig. 11, a. CARTILAGE. 169 The following table gives a synoptical view of the entire glandular system. fCuticular glands. Secreting glands. Cutaneous ^ glands. Glands. v Vascular glands Doubtful glands Epidermal f Sudoriparous glands. glands. (.Sebaceous glands. Epithelial [Mucous follicles. glands. (.Mucous glands. Glands of f , , „ . which is evolved into a parent cell {fig. 217, f), the en- velope of which coalesces through a great part of its circumference with the walls of the parent cell. The part of the envelope of the young cell which is free becomes thickened, and changes into the flat septum, which effects a greater isolation of the now dissevered cells. In this way we often see from three to four cells, of the most recent formation, separated by a bar or cross piece of hyaline substance,* and of these only one, perhaps not one, is a parent cell. 2d. Cytoblasts (cell-nuclei) and cells arise in the hyaline substance, and then grow till they attain the size of the primary and neighbouring ones. 3d. New cells are formed on the periphery, by which the cartilage comes to be augmented by external apposition of parts. Among the permanent cellular cartilages we * An indication that the intercellular or hyaline substance of cartilage is formed and increases from the absorbed cyto- blastema, the mode of growth being by thickening of the cell- walls, probably in consequence of a setting or coagulation of the hyaline substance upon the inner aspects of the cells during "their developement. 174 CARTILAGE. find the cartilaginous septum narium, and the car- tilages of the ala; and point of the nose ; the semi- lunar cartilages of the eyelids ; the cartilage of the external ear and Eustachian tube ; the cartilages of the os hyoides and larynx, with the exception of that of the epiglottis, and the cartilages of the trachea and its branches ; farther, the articular cartilages — those cartilages that cover the articular surfaces of the bones ; the cartilage which terminates the base of the scapula ; the cartilages of the ribs in man ; and the ensiform cartilage of the sternum. The permanent cellular cartilages contain less soluble matter than the cartilages of the hones. Those of the foetus are attacked with great difficulty by boiling water, and do not yield proper gelatine.* § 173. Ossijic Cellular Cartilages. — All the bones of the body have cartilaginous rudiments ; it is only during the process of ossification that the calcareous salts, which finally give them their cha- racters, are deposited. We shall have more to say of these cartilages when we come to speak of the bones, t * J. Miiller* was the first who called attention to the dif- ferent qualities of gelatine as procured from different sources, — a discovery which has led to the distinction of the old proximate principle called Gelatine into two principles designated Chondrin and Glutin : chondrin being the product by long boiling of all the permanent cartilages ; glutin of the animal basis of bone, of ligament, cellular tissue, &c. — G. G. f Ossification often begins in a soft membranous basis. In certain flat bones, as the parietal, nothing like cartilage is to be seen at any step of their growth ; and the shafts of the long * Poggendorff’s “ Annalen,” B. xxxviii. S. 295. FIBROUS AND OSSIFIC CARTILAGE. 175 § 174. Reticular Cartilage. — In the cellular mass destined to the formation of reticular cartilage, so soon as an isolating intercellular substance is visible, we observe new cells evolved in the primary or parent cells, and between these new cells a new hyaline substance, the primary intercellular sub- stance being simultaneously transformed into an elastic intercellular rete, in the meshes of which lie imbedded completely formed cells and others of more recent formation, and mingled with these older and younger nuclei {fig- -59). This variety of cartilage passes in some parts into a highly elastic and extensible reticulation : for example, at the root of the concha auris and of the epiglottis, in which scarcely any trace of cartilage corpuscles remains. Towards the extremity of the cartilage of the concha, again, the network disappears by de- grees, and the structure passes over into cellular cartilage. The reticular cartilages do not afford gelatine any more than the cellular cartilages. In old age, we almost invariably meet with partial ossific deposits in cellular cartilage ; these, however, are very rarely seen in fibrous cartilage, and pro- bably never in reticular cartilage. bones never appear cartilaginous before ossification, like the epiphyses. If it be said, that the membranous matter in ques- sion is merely a soft rudimental cartilage, it might as well be asserted, that granulations or clots of lymph are identical with any tissue which they may be destined to produce. In short, the soft tissue in which the osseous deposit may first be detected in certain flat bones and in the shafts of the long bones, cannot be regarded as identical with the well-known dense cartilage in which ossification begins in the epiphyses and in several flat bones. — G. G. 176 CARTILAGE. § lg". Fibrous Cartilage The true fibrous cartilages are very tough, fibrous, and extensible. They consist of highly elastic parallel filaments, and are, therefore, very different in their structure from the reticular and cellular cartilages ; in fact, as they belong to the fibrous structures they will be more properly discussed in the section that treats of these than in this place. Wherever the fibrous car- tilage assumes the properties of the cellular cartilage, there the microscopic elements of cell-cartilage are found to increase at the cost, as it appears, of the fibres, which become rarer and rarer. Fibro-car- tilage yields no gelatine by boiling. § 176. Ossific Cartilage. — The transparent element of the hones, hitherto regarded as a hyaline substance in which the bone-corpuscles lie scattered, has been generally designated by this title ; but as I shall shew when speaking of the bones that the bone-corpuscles are the nuclei of the bone- cells, and as these have no intercellular matter or hyaline substance between them, it is obvious that the title ossific cartilage, for the transparent ele- ment of bone, is improper. Those cartilages, how- ever, that are destined to become bone, and those that can be shewn to exist as the animal element of bone by the agency of acids, might with pro- priety be spoken of under the name of ossific. The entire skeleton of the bony fishes comes under the same category.* * In the skate, the secondary cartilage-corpuscles of the skeleton are crowded together in groups precisely as in the car- tilages that are destined to undergo ossification. Vide fig. 58, A, which is a section from a costal cartilage of the dog. The areas OSSIFICATION OF CARTILAGE. 177 § I77. Normal Ossification of Cartilage .• — The ossification of the costal cartilages which occurs in the domestic mammalia, especially the horse, although incomplete, may still be reckoned as nor- mal, for it takes place invariably. In the full-grown horse the costal cartilages are always found more or less bony ; the same thing is observed in the middle-aged dog ; and probably it occurs constantly among the carnivora.* § 178. The process of ossification that occurs in the cellular cartilages is always essentially of the same kind ; in the formation of bone in the embryo, in the renovation and repair of broken hones by exu- dative inflammation, in the ossification of the carti- laginous epiphyses, as Mieschert has shewn, in the more tardy ossification of the costal cartilages, and finally, in the ossification of the permanent car- tilages in advanced age, or under other accidental circumstances — in every case the process is the same.! All bony concretions, on the contrary, which around the groups which indicate the boundaries of the primary or parent cells (B) are still visible in some places. The costal cartilages, therefore, evidently stand on the confines between proper cartilage and true bone. * See Mr. Gulliver's note, p. 13. f “ De Tnflam. Ossium,” &c. 4to. Berol. 1836. X In the reparation of fractures some physiologists, as the late Mr. Wilson and Professor Meckel, affirm that the process is just the same as that by which the original growth of the bone took place. There may be certain facts favourable to this doctrine, but there are many at variance with it ; for instance, in the course of reparation of fractures of the shafts of the long bones, a cartilaginiform substance is formed quite unlike any structure observable during the original growth of the same part. The cartilaginiform matter is generally abundant when N 178 CARTILAGE. arise without preceding formation of proper car- tilage, such as we constantly find in arteries, in the dura mater upon occasion, in ossified glandular cysts, &c., although the cellular structure cannot be denied to some of them, still they have seldom or never the texture of true bone. § 179. Ossification of the Costal Cartilages If one of the costal cartilages of an aged person, or of a full-grown domestic animal, be cut across slowly with a knife, certain parts or points will be found bony, others in the state of cartilage, and these pass the one into the other. A section of a cartilage beginning to be ossified presents the appearance represented in fig. 58. Whilst those parts of the cartilage that are remote from the point or points of ossification are remarkable for a regular dis- semination of cartilage cells through their substance, those that are close to it exhibit a clustering or agglomeration of these cells (A) separated by an apparently homogeneous intercellular substance. In these clusters it is not difficult to distinguish cells of older and more recent formation, simple and there is much displacement of the fragments. Some good ex- amples of it in the lower animals may be seen in the Museum of the Army Medical Department at Chatham, — Division, Experi- mental Physiology. It may be added, that in fractures of the patella the new bone shoots from the broken extremities into a dense fibrous tissue, quite unlike the cartilage of which the patella is formed at an early period. See my “ Experiments and Observations on Fractures of the Patella,” Edin. Med. and Surg. Journal, No. 130; and “On the Reparation of Fractured Bones,” Ibid. No. 124. Some illustrative figures are given in the drawings from preparations in the Army Medical Museum at Chatham, fas. 3, plate 9. — G. G. OSSIFICATION OF CARTILAGE. 179 united or blended cells, and smaller and larger isolated nuclei. Where the ossification begins, these clusters are more closely crowded, and are ever more and more distinctly surrounded and enclosed by a delicate line. These lines, speaking of them in the plural, probably indicate primary or parent cells, — those cells which arose in the foetus on the first formation of the cartilages, and within which the secondary cells (A), the prime means of growth in reference to the cartilages, have arisen. From the part B (Jig. 58) the primary intercellular substance is opaque, having become so by deposited earthy salts.* Whilst the bone-corpuscles ( Jig . 60, 5) appear in bone in progress of formation (a), the cartilage corpuscles disappear, and bone-cells (c) are produced in their stead, and these fill the entire spaces 1. The ossification of the foetal cartilages proceeds precisely in the same manner, t The cartilage corpuscles, ever more and more crowded together and compressed, cede the space they formerly occupied to the increasing osseous sub- stance ; this grows constantly more and more opaque, bone corpuscles make their appearance, then ves- sels,!: &c., and the bone is achieved. * Vide also Jig. 69, B. f Fig. 69 and reference in Explanation of the Plates. X Every anatomist is acquainted with the vascular beds in which ossification takes place. As soon as an osseous point can be seen, vessels by which the bony matter appears to have been deposited may generally be rendered apparent by the aid of injections. I have not, however, made any particular observations as to whether the bone-corpuscles or the vessels are first produced ; but the latter, of course, is the common opinion. — G. G. 180 CARTILAGE. This process may be explained in the following manner. The secondary hyaline substance, an ele- ment included within the primary cells, and in car- tilage not to be distinguished from the parietes of the parent cells, is constantly dissolved, and in the fluid state permeates or transudes the walls of the primary cells now become invisible, or it coagulates on the inner aspects of these cells ; out of this cyto- blastema, cytoblasts (the bone-corpuscles) are formed by coagulation and organization of the new hyaline substance, and from them are produced the bone- cells, which comport themselves in the same manner as the embryonic cartilage-cells ; in other words, they form a cellular mass without any interposed matter or intercellular substance. Whilst the recently formed bone-cells are growing, new cytoblasts arise between them and the shrunken parent cells, in the mass of cytoblastema, which is incessantly prepared by the transudation of fluid through the walls of the parent cells, or, it may be, which is laid up by coagulation upon their inner aspects;* the cartilage corpuscles, as said, ever more closely pressed to- gether, disappear ; the nuclei of the bone - cells acquire all the while calcareous salts and become opaque ; the bone-cclls themselves appropriate salts of the same kind, radiated points, nutrient vessels, &c. make their appearance, and the bone is fully formed. § 180. The blood-vessels of cartilage which meet the eye, or which are made conspicuous by * The reverse, consequently, of the mode in which the yolk is formed in the egg, which occurs by a penetration of the cell (the vitellary membrane). USES OF CARTILAGE- 181 ordinary injections, are so few in number, that it does not seem likely that this substance should de- rive the juices necessary to its growth and main- tenance, by imbibition or endosmose from these alone.* Bone, a less decompoundable tissue, is far more freely supplied with blood-vessels than carti- lage ; it is, therefore, probable that the vessels of cartilage are more numerous than they are gene- rally supposed to be,t although it must be allowed that cartilage is rarely reproduced, and that wounds of this substance heal slowly, and generally cicatrize at length without any attempt to supply losses. § 181. The cartilages, from their various pro- perties— their strength, their elasticity, &c. — are very essential elements in the mechanism of the human and animal body. The ossific cartilages probably lend themselves to the irregular and rapid movements of early life, even better than the harder and less elastic bones would do. Tlie per- manent cartilages are employed in the carpentry of parts which, from their function and their posi- * The late Sir Anthony Carlisle instituted some ingenious inquiries into the mode of growth and reparation of the extra- vascular parts of animals, as the shells of snails, oysters, &c. — Vide his paper : “Facts and Observations relative to the con- nexion between vascular and extra-vascular parts in the struc- ture of living organised bodies,” in Lond. Med. Repository , vol. iv. p. 89 (1815) ; and in Thomson’s Annals , vol. vi. p. 174. Some interesting observations on the same subject were recently communicated by Mr. Toynbee in a paper read at the Royal Society. f We are indebted to Mr. Liston for an admirable demon- stration of the existence and arrangement of the blood-vessels of diseased articular cartilage. — Vide Trans . Med.-Chir. Soc . vol. xxiii. — G. G. 182 BONE. tion, evidently require elasticity and yet firmness in their construction : in such parts, for instance, as the external ear, the larynx and trachea, the extremities of the bones where they form articu- lations, &c. BONE. § 182. The bones may he said to be produced immediately from the mutable cartilages, and they are well known to be readily reduceablc to the state of cartilages again, which retain the precise struc- ture of the bones from which they were obtained. Bones are hard in the ratio of their density, and of the quantity of calcareous salts they contain.* They * It has been commonly supposed that the difference in the physical properties of the bones of the blood and cart-horse are connected with a marked difference in the proportions of the earthy and animal matter ; but Dr. Davy’s observations are opposed to this opinion, as will appear from the following extract from his “ Researches,” vol. i. p. 394 : — Calcareous Animal Matter. Matter. Pure -bred horse, — metatarsal bone, specific'! gravity 1854, and after having been subjected | 65-77 to air-pump, 2033 J Low-bred troop-horse, — metacarpal bone, spe-i cific gravity before action of air-pump 2010, 65-78 and 2077 after J Blood-horse, — compact part of shaft of humerus, 'i before being subjected to air-pump, specific 1 69-44 gravity 2045, and 2092 after J Dray-horse, — similar part of humerus, before^ action of air-pump, specific gravity 2000, [ 70-8 and 2126 after J 34-23 34-22 30-56 29-2 Dr. Davy further remarks, after a table of the proportion of animal and calcareous matter in diseased bones, what very slight agx-eement there is between the quality of hardness and of soft- ness of bone, and the proportions of calcareous and animal PROPERTIES. 183 are of a yellowish, a bluish, or reddish white in different instances, and they possess a very consi- derable degree of elasticity. The specific gravity of bone varies considerably, being in relation to the density and amount of saline impregnation of the specimen examined ; it generally lies between 1 *80 and 2*03. * The animal matter of hone is easily re- moved by the action of caustic alkali and of a high temperature If the bone be exposed to heat in contact with air, the remaining earthy matter co- heres much less firmly than it does when the ex- posure is in a close vessel or without the access of air ; the animal matter, in the latter case, is only charred, and the bone retains its shape in great part, and, in some measure, its consistency. Dilute acids remove the earth, and the cartilage remains behind. The cartilage of the foetal bones is but very sparingly soluble in water, and does not yield proper gelatine by long boiling ; the cartilage of the bones of adult animals, on the contrary, is in a great measure and readily soluble in boiling water, and yields an abundance of jelly. t The calcareous salts of the bones lessen the liability of the component cartilage to undergo decomposition in so notable a manner, that they decay with extreme slowness ; hidden in the earth, or sunk in water, they proclaim matter, confirming the conjecture that more seems to depend, in relation to these qualities, on the arrangement of the ingredients than on their respective proportions. — Researches , Rhys. and Anat. vol. i. p. 403. — G. G. * See Dr. Davy’s “ Observations on the Specific Gravity of different parts of the Human Body.” — Researches, vol. ii. p. 253. f Vide note to § 172. 184 BONE. the existence, at periods variously remote from that in which we live, not only of numerous species, but of entire genera of animals that are now extinct. These fossil organic remains, as they are called, sometimes differ, as regards their state, in nothing from hones of existing animals that have lain long in the ground, or been long exposed to the action of water. At other times, however, they are truly mineralised , having become penetrated with cal- careous or siliceous matter, when they are as hard and unchanging as jasper or marble.* Even when thus penetrated, hones retain their structure, a cir- cumstance which is at once apparent when a thin slice is placed under the microscope.! * In the parietal bone of a skull probably 3000 years old, from an ancient tomb at Cerigo, Dr. Davy found 26-2 per cent, of animal matter ; and in a bit of the zygomatic process of an ancient Egyptian cranium from a tomb at Thebes, there was 23-9 per cent, of animal matter. “ In the bone-breccia of the Mediterranean, so widely scattered, I have been able to detect a just perceptible trace only of animal matter; and in the teeth of the squali, which occur in the tertiary formations of Malta and Gozo, I have not been able to detect even a trace of it. In an enormous tooth of one of these fishes now in my possession, I carefully sought for animal matter, but in vain. They and the fossil bones generally which have not been exposed to the air, owe their strength and hardness to a kind of cement of carbonate of lime, which they all acquire. Judging analogically from the partial effect of a known period of time, what an idea of vast antiquity is conveyed by the circumstance of the total destruc- tion of the animal matter of bones!” — Researches, Phys. and Anat. vol. i. p. 399. — G. G. j- This circumstance has recently been taken advantage of, more especially with reference to the teeth, in determining the species or family to which the animal belonged, of whose ske- leton some small fragment only is discovered. With a piece of a DEVELOPEMENT. 185 The bones, with the exception of the crowns of the teeth, are inclosed by the fibrous periosteum. The long bones of mammals contain the marrow, which is merely a finely cellular fat, inclosed within the lining membrane of their internal cavities. The flat bones consist of two tables, separated by a can- cellar, or spongy substance, called diploe, which is either occupied with marrow, or is hollow, in which case it is lined with a delicate mucous membrane. The cubical, or rounded hones, such as those of the carpus and tarsus, and those of a mixed character, consist of a spongy tissue with included medul- lary cells or cavities, and are commonly bounded by a very delicate layer of dense or vitreous bony substance. § 183. The developement of the bones in the foetus takes place sooner or later in different species of animals, according to the time which the embryo itself requires for attaining the maturity that will fit it to begin an independent existence. The bone-cells begin to be formed in certain points — centres of ossification : these are aggregations of oval bone-cells, from which the ossification spreads over the rest of the cartilage. Small rounded bones have usually but a single centre of ossification ; irregular bones again have several centres ; cylindrical hones have at least three, one in the middle, and two others for the epiphyses or end portions. tooth we can generally say that the skeleton of which it formed a part was that of a mammal, a reptile, or a fish, and often even make more particular deductions. — G. G. 186 BONE. Microscopic Analysis of Bone. § 184. A delicate slice of a cylindrical bone under a low power exhibits (vid efig. Cl) canals ( b , c), which for the most part run parallel with one another (/>), and are connected by cross or anasto- mosing branches (c). In the recent bone these channels contain blood, which during life is con- veyed by the nutrient vessels that enter and quit the bone in different places. The spaces between the vessels («) constitute the proper substance of the bone ; this consists of bone-cells, the nuclei of which are called bone-corpuscles. These in fig. 61 appear as simple points ; under a higher power, as in fig. 70, they have distinct and definite forms. From the elongated bone-corpuscles (a), which are without obvious nucleoli, extend fine radiations, the canaliculi chalicophori of Muller, on every side to the confines of the cell ( b ). A good view of the cells of bone is obtained by inspecting a delicate transverse section of one of the grinding teeth of the horse (the appearances are represented in fig. 68); the cells are seen extending from the bony substance a , b ; a, b', half way into the enamel b, b' . These cells all contain a nucleus, some of them contain two. The same structure may, however, be demonstrated here and there in a fine section of any bone, by soaking it first in a solution of nitrate of silver, drying it, and then dipping it in a solution of common salt, after which it must be polished. These cells of bone do not appear to have any vitreous substance interposed between them. They OSSIFICATION. 187 surround the vessels {fig- 65, c), in the form of concentric laminae (b), and lie betwixt them with more or less of an obvious parallel arrangement, (a.)* In the flat bones the vessels form a common net- work (fig. 66). The spongy bones in general con- sist of a reticulation of compact bony substance, which encloses cavities full of fat cells. § 185. In the embryos of our larger domestic animals we discover the incipient ossific points about the sixth week from conception ; in the common fowl they are visible as early as the ninth day, and in some of the bones bone-corpuscles are even then already obvious. The ossification extends from these points, in rays in flat bones, in long bones in the direction of their length. Some bones are earlier formed than others : the lateral portions of the bodies of the vertebrae appear at a very early period, and between the two rows which they form lies the chorda dorsalis. The separation exists in the calf in the eighth week ; the lateral parts of the vertebral arches are only united towards the tenth week. Ossification in the bones of the head begins in the lower jaw, then in the os frontis, and next in the circumjacent bones of the face. The middle portions of the ribs are ossified at an early date ; and nearly simultaneously, the middle portions of the great bones of the ex- tremities shew points of ossification, the thoracic extremities being always somewhat in advance of the abdominal limbs. The smaller bones of the extremities follow, and finally the square or rounded * Consult the figures from G1 to 66 and the appertaining explanations of the plates. 188 BONE. bones of the carpus and tarsus. The blood-vessels are relatively larger and more numerous the younger the bone is. No nerves other than those that pene- trate along with, and apparently belong to, the blood- vessels, seem to exist in bone. Chemical Constituents of Bone. § 186. Bones subjected to dry distillation in closed vessels yield an empyreumatic oil, an empy- reumatic acid, carbonate of ammonia, and a variety of gases ; and there remain behind carbon, phos- phate of lime, and a little phosphate of magnesia. In Papin’s digester the cartilage of bone is dissolved out, and appears in the shape of gelatine. In the adult the cartilage forms about one-third part of the whole mass of a bone. One hundred parts of the dry bone [of the horse ?] were found to consist of Cartilage 32’ 17 Vessels 1*13 Basic phosphate of lime with a trace of fluate of lime 53*04 Carbonate of lime 11*30 Phosphate or carbonate of magnesia 1*16 Carbonate of soda with a little chloride of sodium 1*50 100*30 § I87. In the foetus and young creature the animal matters predominate ; the earthy increase with age ; so that the older the individual, the harder and more brittle are the bones.* The carbonate of * The proportion of calcareous and animal matter varies under circumstances which do not yet appear to have been pre- CHEMICAL CONSTITUENTS. 189 lime which is found in the skeleton of the mammal is typical of a lower grade of organization than the phosphate of lime ; the former predominates at the bottom, the latter at the top of the scale of animate cisely explained. Thus in recent bones, from a young person aged about 15, Dr. Davy obtained the following results, viz. — Calcareous Matter. Animal Matter. Parietal bone 58-8 41-2 Tibia 53-6 46-4 Fibula 44-0 56-0 Ilium 45-0 55-0 Femur 47-0 53-0 Dr. Davy’s analyses shew that the proportion of earthy matter does not always increase with age, as in the following examples, in all of which the parietal bone was the subject of experiment ; and the specimens were previously thoroughly dried, by exposure to a temperature of 212°, till they ceased to lose weight, — a circumstance, as he justly remarks, of some import- ance in comparative experiments : — From a man set. 20 Calcareous Matter. 6G-9 Animal Matter. 33-1 Ditto set. 31 70-2 29-8 Ditto set. 52 68-5 31-5 Ditto set. 45 66-6 33-4 The bones of young children are known generally to possess a smaller proportion of earthy matter than those of adults ; yet to shew how perplexing, in the present state of our knowledge, the subject is, the subjoined analyses are selected: — Calcareous Animal Matter. Matter. Lower jaw of an old person (No. 10, p. 385) 56-6 43-4 Ditto of a child (No. 6, p. 392) 57-2 42*8 Ditto of a fcetus, between five and six months (No. 9, p. 393) 56-0 44-4 These results, of course, are at variance with the majority, but they are well calculated to excite further inquiry. — Vide Researches, Phys. and Anat. vol. i. p. 384, et seq G. G. 190 BONE. creation ; and in morbid discrasise the carbonate sometimes appears at the cost as it were of the phosphate, and this, too, by so much the more as there is a greater amount of alteration of structure. In this state of things it is very common to find associated a partial metamorphosis of the fibrinous tissues (vide § 96), — a conversion of cartilage into fat, for instance.* § 188. In the osteology the bones are particu- larly considered in all that regards their forms, processes and elevations, their pits and depressions, their connexions, &c. &c. § 189. Projections. — When elevations form im- mediate continuations of bones they are called apo- physes ; when they are separated from the bones by a layer of cartilage, they are denominated epi- physes. These last are ossified from a distinct point, and only become united to the bones upon which they are placed by the gradual ossification of the connecting cartilage, when they are changed into apophyses or processes. The consideration of the various forms of bony process belongs to the * In Dr. Davy’s work on the Interior of Ceylon is an account of the dissection of a leg in which a large quantity of oil was found in the capsule of the knee joint in the place of synovia : the case was one of elephas. The substance of some of the viscera of carnivorous animals which have died in con- finement is often gorged with oily matter. In the parenchyme of the kidneys of the leopard, for example, though these organs appeared otherwise healthy, and the animal was generally not fat, I have seen so much oil that it might be pressed out in con- siderable quantity. Some preparations shewing the fact were sent to the Museum of the Army Medical Department at Chatham. — G. G. PROJECTIONS AND DEPRESSIONS. 191 descriptive anatomy, so that it will be enough in this place to enumerate the different kinds that have been specified ; these are : — 1st. Capitular processes : articular terminal sur- faces of a more or less rounded form covered with cartilage. 2d. Button -like processes , connected with the hones by a broad base, covered with car- tilage, smooth, round, and serving as means of articulation. 3d. Eminences of impression and of reflection, and odontoid processes. 4th. Tro- chanters, tubers, tuberosities, strong, rough pro- cesses for the attachment of muscles, ligaments, &c., and serving as levers. 5th. Ridges, long, linear, sharp, and rough margins upon flat bones. 6th. Lines, long, little-raised ridges. 7th* Spines, long pointed processes. § 190. Depressions. — These either include ar- ticular processes, and are therefore covered with cartilage and smooth ; or they lodge or enclose cer- tain organic parts ; or they constitute cavities or sinuses of different capacities, which are covered with mucous membranes. The following kinds of depression have been enumerated : — 1st. The deep and shallow articular depressions — the cotyloid and glenoid cavities. — These receive the more or less perfectly globular heads of hones for the constitution of joints having the freest motions. 2d. The trochlea, groove, or channel, an elongated shallow depression. 3d. The canal, a complete or close channel. 4th. The foramen or hole, a de- pression that passes through a bone. 5th. The cleft, a fine slit passing across some portion of a bone. 6th. The notch or cleft that does not go 192 BONE. completely through the bone, and gets narrower as it goes deeper. 7th- Sinuses or antrci; these are hollow spaces lined with mucous membranes between the tables of flat bones. § 191- Connexions. — Bones are connected in different ways with one another according to the properties and uses required in the articulation. Sometimes they are freely movable one on another — diarthrosis ; sometimes the motion is very limited — amphiarthrosis ; and sometimes it is nil — syn- arthrosis. 1st. In the movable articulation, the opposed ends of the bones are covered with articular cartilage, and fashioned severally for the encounter that takes place, enclosed within a common synovial capsule, and kept together without any implication of the required movement by means of ligaments. The movable articulation is divided into different kinds : (a), the enarthrosis or ball and socket joint, such as those of the hip and shoulder ; (Z>), the hinge or ginglymus joint, like those of the knee, ankle, &c. ; (c), the pivot joint, of which a perfect example is furnished in the articulation between the atlas and vertebra dentata ; (d), the arthrodial or limited joint,, of which we have examples in the articulations of the carpus and tarsus, where the bones merely glide backwards and forwards for a little way upon one another. 2d. In the mixed or amphiarthrose articulation, the bones are connected by some interposed sub- stance,— cellular or fibrous cartilage. The motion here is entirely referable to the elasticity of this interarticular substance : we have examples of it in the intervertebral and pelvic articulations. TIIE SKELETON. 193 3d. In the synarthrose or immovable articula- tions the bones abut immediately upon one another, and their union is accomplished variously : (a), by suture, when the edges of the bones penetrate each other mutually by jagged offsets ; (5), by scyn- delesis, when a ridge in one bone is received into a furrow of another ; (c), by harmony, or false suture, when the edges of the hones merely meet without penetrating each other by large and obvious offsets ; (rf), by gomphosis, when a part is implanted in the manner of a wedge or nail, as are the teeth in the alveoli of the jaws. § 192. The skeleton is the foundation and frame-work of the animal body, a system of props and levers for the muscles of voluntary motion to accomplish the behests of the mind withal ; a means of forming various cavities in which the viscera are contained. Its parts, like all the rest that belong to voluntary motion and sensation, are symmetrical and in segments ; in other words, an antero-posterior plane divides it into two equal halves, so that on the right and on the left side similar bones in like number are encountered, and in the middle line or plane of section single bones, but divided into two similar halves. The skeleton is divided into head, trunk, and extremities. In the head we distinguish the bones of the cranium and those of the face. In the trunk we have the vertebral column, the ribs, the sternum, and the pelvis. The anterior, atlantal, or thoracic extremity consists of the scapula, clavicle (where present), humerus, radius and ulna, carpus or wrist, metacarpus, and digital phalanges. The posterior, o 194 TEETH. sacral, or abdominal extremity comprises the femur, tibia and fibula, tarsus, metatarsus, and digital phalanges.' The accessory bones — the os hyoides, sesamoid bones, marsupial bones, os penis, &c., are connected variously with the proper skeleton by means of cartilage or ligament •, but the cardiac bone of the ruminants has no connexion with the skeleton at large, and belongs to another organic system. TEETH. § 193. The teeth were long and uniformly, by all the early writers on anatomy, classed among the bones ; but by and by, and under the influence of new views, they came to be reckoned among the horny tissues, and this not without apparent reason ; for, though the teeth in point of chemical composi- tion and texture belong obviously to the bones, still in their extrinsic situation, their mechanical relations to external things, and their connexions with the processes of the corium which engender and con- tinue to maintain them, they as evidently appertain to the cuticular formations, and bear a close affinity to the nails and hair. The most recent inquiries of all, however, those of Miescher, J. Muller, Ret- zius, [Nasmyth, Owen], &c. have clearly shewn the teeth to be modified or epithelial bones, so that they cannot now be detached from the osseous system. In the teeth of the lower animals, as many as three different substances are readily distinguished : 1st. the enamel or vitreous substance ; 2d. the proper substance or ivory ; 3d. the bone or cement. § 194. Enamel, Vitreous Substance. — This is ENAMEL. 195 the hardest part of the teeth, and indeed of the animal body ; it is, however, brittle, of a bluish white colour, and semi-transparent ; it generally forms the outermost layer of the teeth ; although any interchange of substance is hardly conceivable in the enamel, it nevertheless maintains its appearance and properties unchanged through the whole period of life ; it is, in fact, only affected by drying, an elevated temperature, and acids. In man, and the quadrumana and the carnivora, it forms the outer layer of the crown but in the horse and the rumi- nants it is covered by a crust of bony substance (fig* 67, a, bony substance, b, enamel). On the rubbing or grinding surface of the teeth of these animals, however, it always projects more than the other parts, its greater hardness preserving it from wearing down by attrition in the same degree as these. In man and the carnivora, and in the incisors of ruminating animals and the hog, the enamel forms a simple external layer, and so surrounds the other substances on the crown ; in the grinding teeth of the horse and ruminantia, again, it is inverted upon the rubbing surface into the bony substance of the tooth, so that when the edges of the inverted por- tion are worn off, it forms two layers, between which the proper substance of the tooth is conspicuous, one layer being external {Jig. 67, b), another in- ternal (e), including, as just said, the ivory or proper substance of the tooth (c) between them. The hollow of the involuted layer of enamel in the grinding teeth of the horse, is filled up by the external bony substance ( f). * Vide note, p. 200. TEETH. 196 Microscopic Examination of the Enamel. § 195. The enamel {fig. 68, b, on, and g, hi), consists, according to Purkinje, of closely com- pressed four cornered (Retzius* says six cornered) slightly bent prisms, which stand in the direction of the lamellation or axis of the tooth nearly perpen- dicularly, so that the one end is either external and free, or external and in contact with the outer layer of bony matter, as in the horse {fig. 68, b), the other end being internal and directed to the proper substance of the tooth {fig. 68, f) ; t in the in- voluted portions, of course, the reverse of this ar- rangement obtains {fig. 68, b, on). The prisms are indicated in fig. 68 by the fine lines h, and as they present themselves under such a power as the one employed ; inspected from the base and highly magnified, they appear as in fig. 7 % b, or in fig. 186. The enamel of a delicate section of a tooth, when magnified, has a yellow colour, and is sepa- rated by an intermediate brown streak from the greyish-blue coloured substance of the tooth. The prisms of the enamel unite with the bone cells which half penetrate the enamel {fig. 68, b, b) in the same way as the fibres of the tendons unite with the conical ends of the primitive muscular bundles {fig. 51, a at 1). § 196. In the foetus the enamel is enclosed by a * Muller’s “ Arcliiv.” 1837, S. 486. Taf. xxi. f A transparent layer of basalt would convey, on the great scale,- a good idea of the arrangement of the enamel prisms. The enamel also resembles, to a certain extent, a compressed cylinder-epithelium (fig. 46, b, c ). PROPER SUBSTANCE. 197 membrane which, according to Schwann, is beset internally with cells, which are prolonged from the surface of the membrane inwards, and form the enamel-needles or prisms, which, as they grow, are ever more and more compressed, so that they be- come six sided by their mutual contact, whilst they are becoming ossified and their nuclei are disappear- ing. These cells can be shewn still to exist in the enamel by the agency of dilute hydrochloric acid. Chemical Composition of Enamel. § 197* Pure enamel contains very little animal matter ; it consists almost entirely of inorganic sub- stances, viz. : Phosphate of lime and fluate of lime .... 88'5 Carbonate of lime 8-0 Phosphate of magnesia 1*5 Animal matter, alkali, and water 2-0 100-0 Proper substance ; Tubular substance ; Ivory. § 198. The Proper Substance forms the largest portion of the tooth, and, at the same time, constitutes the kernel of the structure. It extends from the apex of the fang to the rubbing surface of the crown, which, in worn teeth of the human subject, together with the investing crust of enamel, it composes entirely. On the grinding surface of the teeth of the horse, where there is an involution of the enamel, it is contained betwixt the outer and inner layer of this substance (Jig. 67> c. ; fig. 68, k, l, k~). To the naked eye the proper substance appears slight! v 198 TEETH. semi-transparent, yellowish in colour, and finely streaked, or fibrous ; polished, it becomes nacre- ous and opalescent. It is harder than other bone, but not so hard as enamel. In the long axis of a tooth we observe an elongated canal, the canal of the tooth {fig. 68, /.), which opens at the root, or fang, and extends towards the grinding surface, in- creasing in width as it advances. In this canal are contained the vessels and nerves of the tooth, and the younger the tooth the more ample is the canal, or cavity. In the foetus, and in early life, it in fact contains the pulp of the tooth, the part which, according to the views of physiologists of the last age, secreted the tooth, [which, according to present opinions, is converted into the tooth, having calca- reous salts deposited in it, in the same manner as ossific cartilage in other situations]. § 199* Microscopic Analysis of the Proper Substance. — In fine slices of teeth, the proper sub- stance appears of a bluish-grey tint, it is an other- wise homogeneous hyaline substance, penetrated by delicate, slightly sinuous, cylindrical tubuli, lying close and parallel to one another {fig. 68, Jc, l, /r,), beginning with fine openings in the central canal (/), and running obliquely outwards and towards the crown. When they reach the enamel, or, as hap- pens in the roots of the human teeth, the bone, they ramify very minutely, and seem to penetrate the enamel, or the bone itself ; with these fine ramifications, true bone-corpuscles are connected, a fact which, after Iletzius, I have ascertained dis- tinctly in examining the teeth of the horse. The tubuli in the fresh and living tooth, contain a red- BONE OR CEMENT. 199 dish fluid ; they are too minute to admit the blood corpuscles. The proper substance is developed in the foetus from cells which, undergoing elongation, their ex- tended and hollowed nuclei at length form the tubuli. The ramifications of the tubuli, especially towards the extremities at and in the enamel, present pre- cisely the same appearance as the radiations of the bone-corpuscules. The cells are produced by the pulp, from which fine fibres pass into the tubuli. § 200. Chemical Composition of the Proper Substance. — The substantia propria appears to possess different degrees of hardness in the teeth of different families of animals, and to contain its constituent elements in different proportions. In the mammalia it has been found to consist of — Animal matter 28-0 Phosphate of lime and fluate of lime 64-3 Carbonate of lime 5*3 Phosphate of magnesia 1-0 Carbonate of soda and a trace of common salt 14 100-0 Bone of Teeth ; Cement ; Crusta Petrosa. § 201. In the simple teeth of man and the carnivora, the bone is met with as a simple layer covering the fangs ; in the teeth of the ruminantia and other animals, however, the horse, for example, where there is involution of the enamel, the bone is met with as a double layer, first surrounding the teeth entirely (fig. 67, a , a, a), and then inverted into their substance ( /), from the grinding aspect through the middle of the crown, to the place of its 200 TEETH. transition into the root.* Here the bone presents itself in the guise of a piece let into the enamel (e). In the young tooth there exists a brown coloured depression in the middle (g), which, in the incisors, has the shape of a compressed cone ; this constitutes what is called the mark of the horse’s tooth. The bone is the softest part of the tooth ; it is less transparent than the other elements. It is of a milk-white colour within, externally it is often yellowish. It is only produced after the enamel and ivory have been formed, and is rather to be viewed as a crust superadded to the tooth, than as an essential portion of its structure. § 202. Microscopic Analysis of the Bone of Teeth.— The internal and external bony substance present the same appearances under the microscope : they look like ordinary dense bone. Their bone- corpuscles (jig. 68, ck) are of large size, and lie in layers concentrically disposed, and that increase in thickness externally (c, cj ; the radiations proceed- ing from these corpuscles, however, are never so distinct as they are from those of ordinary bone ; occasionally the limits of single bone-cells may be detected towards the line of contact between the * The recent observations of Mr. Nasmyth would lead us to believe that the simple teeth of man and the carnivora were in- vested precisely like those of the ruminants, &c., by a continuous but very delicate film of cement. In the human subject, Mr. Nasmyth succeeded in tracing this film on the whole surface of the enamel and fang of the tooth in one continuous envelope, and he even removed it from the crown in the form of a distinct capsule. He proposes to term it “ the persistent dental cap- sule.”— Vide Med.-Chir. Trans, vol. xxii. p. 312. London, 1839. — G. G. FORM RELATION’S. 201 crust and the enamel, where the cells are seen actually to penetrate the enamel (h, V). The crusta petrosa has its hlood-vessels like bone, running in canals, but they are few in number ; they are of considerable size, however, and generally course from within and from the root outwards and towards the crown. § 203. In a chemical point of view, the bone or cement appears to he of the same essential nature as the compact or vitreous portion of common hone, with this difference, that the quantity of its earthy salts is relatively greater. In adult and old ruminants the crowns of the teeth may often he observed shining with a metallic lustre as if they were bronzed ; this is owing to the deposition of many fine strata of concrescible matter from the saliva. External Form of the Teeth, and their Relations to the Jaws. § 204. The teeth vary in number, form, posi- tion, relations to the jaws, &c. in different animals. They are essential parts in the economy of the mouth and serve in man and the mammalia for the prehension and division or trituration of the food, sometimes as weapons of offence, and sometimes as means of separating the newly-born offspring from the after-birth. According- to their form and destination teeth are divided into incisors, laniarii or canines, and grinders. The crown projects beyond the gum ; the root is concealed by the gum and alveolus, and in the incisors and canines is simple, in the grinders 202 TEETH. compound. Between the root and the crown a con- stricted portion is apparent in some teeth, and this is the neck of the tooth, the part which is embraced by the edge of the gum. In the intermaxillary bones of the solidungula, of the hog and of the carnivora we find six incisors, opposed by the same number in the under jawT, — twelve therefore in all ; the number of incisors in man is eight in all. The intermaxillary bones of the ruminantia are toothless ; the lower jaw, how- ever, is furnished with eight shovel-shaped incisors. The incisors, whether opposed or not, serve for the prehension of the food in the lower animals. The canines in our domestic mammalia are somewhat curved in their form, and stand isolated or apart, midway between the incisors and grinders. The stallion has four of these teeth, which are called tushes ; in the mare they present themselves as mere rudiments. The canine teeth serve as formid- able means of offence in some cases, as in the hoar ; and in the carnivora as powerful instruments for securing and tearing a prey. The molar teeth are generally present in equal number in the upper and lower jaw. In man and the hog the crowns of these are divided into from two to four points ; in the carnivora they are narrow and sharp, and act like the blades of scissors ; in the frugivora again they are broad and rough, the inequalities on the grinding surface being main- tained by the different degrees of hardness possessed by each of the three substances entering into the constitution of the teeth {fig. 67)- The grinders have from two to four roots. In man they are FORMATION. 203 twenty, and in the horse, ox, and sheep, twenty-four in number ; the hog has as many as twenty-eight of these teeth ; the dog has twelve in the upper jaw and fourteen in the lower jaw. § 205. The replacement of the deciduous or milk set of teeth by the permanent set, which occurs in youth, extends to all the incisors ; to the cuspidati in man, the dog, and the hog ; to the eight most anterior molars in man, and to the twelve corresponding teeth in the horse, ox, and sheep ; in the dog, to the second, third, and fourth molars ; in the cat, to the second and third in the upper jaw, and to the first and second in the lower jaw. Formation of the Teeth in the Foetus. § 206. This begins at an early period. Within the alveoli sacs filled with a liquid cytoblastema are first produced, within and from which, but connected with the sacs, arise, perhaps from the nuclei of the parent cells, simple or internally wrinkled vesicles, — the germs or pulps, which prefigure the crowns of the future teeth. Each molar tooth is evolved from several such vesicles. The three substances of the future teeth are produced by a like number of dis- tinct layers of cells, comparable to the three layers of the germinal membrane, which soon ossify and exhibit the hollow shell of the crown, in which the cytoblastema gradually fashions itself into the pulp, whilst externally it is used in forming the tooth ; the crown of the tooth is strengthened by constant additions from the pulp within, and augmented in size by additions from the enamel- membrane without ; 204 TISSUES. (the internal cavity of the tooth is consequently con- tinually lessening). Meantime the root is growing, and with its progress the tooth is rising from the socket, until it finally bursts through the outer layer of the gum, and comes into contact with the cprrcsponding tooth of the opposed jaw which has been developed in the same manner. OF THE TISSUES. § 207. The organic structures, composed for the most part of similar elements, are commonly spoken of under the title of tissues . I mean to restrict this appellation to those that are made up of fibres and filaments, as the name seems to me well applied here, but to be used amiss with reference to the structures designated hyaline, and to those that consist essentially of cells ; for example, the adipose, pigmentary, horny, cartilaginous and osseous. The proper tissues comprehend elastic tissue, fibrous tissue, and filamentous tissue ; the last being subdivided into cellular, tendinous, ligamentous, fibro- cartilaginous, contractile, and muscular. ELASTIC TISSUE INTERCELLULAR RETE. § 208. To the naked eye the elastic tissue appears as a fibrous, pale chrome or ochre yellow coloured, dull texture : it is generally seen in the shape of soft membranes either alone or connected with cellular tissue, tendons, cartilages, See. ; it forms an integral part of all the elastic membranes ; it possesses such elasticity that it can be drawn out very nearly to twice its original length, and yet ELASTIC TISSUE. 205 contract again to its old dimensions. It is divisible into flat strings, and is much more easily torn than any of the structures composed of round filaments ; the torn ends and edges are regular and smooth. The component fibres and fasciculi of elastic tissue interlace freely in different directions, and form smaller meshes and larger interspaces. This ar- rangement is very conspicuous in the ligamentum nucha; of the solidungula and ruminantia. Elastic tissue appears to be scarcely more sensitive than bone. It is very sparingly supplied with ves- sels ; and of special nerves it seems to have few or none. § 209- Chemical Analysis of Elastic Tissue The chemical constitution of elastic tissue appears to be peculiar ; but the point has as yet been little investigated. It yields no gelatine by long boiling, and is, indeed, so little affected by boiling water in its texture, colour, and general physical properties, that this agent, so powerful in its effects upon the animal textures at large, may be said to be impotent as regards the elastic tissue.* It may be kept in alcohol for years without undergoing any change. Left to itself, it putrifies with difficulty ; macerated in water its superficies becomes changed into a * After ten hours’ boiling in water. Dr. Davy found that the middle coat of the aorta and pulmonary artery was rend- ered more friable, but not more transparent, and not in the least gelatinous : it was less weakened and altered by the opera- tion than muscle. The effect of long continued boiling on the ligamentum nuchse of the ox was similar. “ On the Effects of Boiling Water, and of Boiling, on the Textures of the Human Body after Death.” — Researches, vol. ii. p. 322. — G. G. TISSUES. 206 slimy-looking matter ; internally the structure re- mains for a very long time unchanged. It is also found powerfully to resist the process of digestion. Dried it becomes brown, transparent, but not brittle as do the cellular cartilages; bent backwards and forwards repeatedly or beaten, it separates into white fibres like whalebone. § 210. Microscopic Analysis, Origin and De- velopement of Elastic Tissue In the mode of its developement, and the nature of its elements elastic tissue differs essentially from the other fibrous and filamentous formations, bearing great affinity to the ossific cartilages. In the embryonic mass of cells destined to the formation of elastic tissue, stratifications are observed like those of the multi- lamellar cuticles. The cells suffer elongation in the direction of the future fibrillation, and become flatly fusiform, as in the fibrils of cellular tissue, but they do not cohere in this instance ; they re- main isolated with sharp pointed extremities amidst the consolidating intercellular substance. In the parent cells of elastic tissue, as in those of cellular car- tilage, new secondary cells are abundantly produced. Whilst the intercellular rete of the stratified cellular membranes becomes independently organised, the cells themselves are either dissolved and disappear, or they remain for long periods, or, finally, they en- dure for the whole term of life. In this way, in all likelihood, is the pure elastic tissue every where produced, — a tissue which, in the mode of connexion of its fibres, bears the strongest resemblance to the capillary vascular rete, as may be seen by compar- ing the highly magnified teased-out, piece of elastic ELASTIC TISSUE. 20? tissue from the middle coat of the aorta represented in fig. 55, with the less strongly magnified capillary vascular rete of the bones of the skull depicted in fig. 66, and with other representations of capillary reticulations, those, for instance, of figs. 140, 144, and 145 ; the continuous elastic tissue of the liga- mentum nuchse (fig* 54) may also be contrasted with the capillary vessels of a muscle (fig. 14*2). The transition of the intercellular rete with poly- gonal meshes into a continuous elastic tissue, I have endeavoured to represent in fig. 225. § 211. The fully formed elastic tissue consists of prismatic, frequently four-sided, rigid fibres, from the - — r- tt th to the -^Trth of a Paris line in diameter. These fibres are even in their course, and sharply de- fined ; they divide furciform fashion, and inosculate at all angles from the most acute to the most obtuse. o The intervening meshes which result from these interlacings and anastomoses are here of like form and magnitude : thev are of the most dissimilar shapes and sizes. The fibres individually as well as collectively are highly elastic. The elastic tissue of the ligamentum nuchse be- longs to the regular and continuous class of such structures. Its fibres are straight, from four to six- sided ; its meshes are so long relatively to their breadth, that they seem often scarcely to form a slit (fig. 54, b ). The structure is only rendered conspicuous when the hand is stretched laterally (a). The elastic tissue of the fibrous or middle coat of the arteries is much more irregular and intricate (fig. 55). The fibres here are of different thick- nesses ; they are frequently flat, and the meshes of 208 TISSUES. different sizes, and mostly polygonal or rounded in figure. The elastic tissue is also commonly enough met with very free from admixture, in the yellow liga- ments and membranes : such, for example, as the anterior and posterior bands that pass between the first vertebra of the neck and the os occipitis, the hands that connect the arches of the other vertebrae, all the yellow bands or ligaments of the os hyoides and larynx : for example, the hyo-epiglottidean band, the hyo-thyroid hands, the tliyro-epiglottidean band, the thyro-arytenoidei bands, &c. Farther, the yel- low membrane, which in the horse especially, covers the pectoral portion of the serratus magnus and the fleshy origins of the external oblique of the abdo- men, and then expands and is lost in fine tendinous- looking fasciae. The elastic tissue also occurs mingled with the proper element of other aponeu- roses ; and it even constitutes an integral part of the skin and mucous membranes. In the cartilages of the external ear and of the epiglottis, and indeed of reticular cartilage generally, it forms a constant element. In some places its meshes are seen filled with single or with several cartilage-cells, or with cells and nuclei together {fig. 59). Even in fibrous cartilage elastic tissue appears very constantly to exist mingled with the proper cartilage-fibres. A delicate elastic tissue enters into the struc- ture of various parts of the eye-hall ; of the ciliary ligament, for example {fig. 56, 1), and of the iris (2), where its meshes are relatively large. The clastic fibres that are readily demonstrated in the ELASTIC TISSUE. 209 finer ramifications of the bronchi {fig. 49, C), and in the coats of the larger veins, are of the same undulating and delicate character as in the eye. The blood-vessels of elastic tissue form a scanty and wide-meshed reticulation. I have never been quite certain of having seen its proper nerves. Elastic tissue is found in every situation where a high degree of elasticity and mobility is required. The middle coat of the arteries reacts powerfully, by its elasticity or elastic contractility, upon the blood thrown into them at each stroke of the heart : the vessels then yield, and the pulse is felt ; but the vessels by their resilience immediately shrink again, and press on the column of blood in one continuous stream, acting in the same manner pre- cisely as the air-vessel in an hydraulic machine. Elastic tissue, if injured, is very imperfectly re- produced ; it is, in fact, replaced by a dense fibrous cicatricular substance. § 212. For the sake of natural connexion, it becomes necessary to remark here, that the rudi- mentary matter out of which the capillary rete of the blood-vessels is formed, as well as that from which elastic tissue and bone are produced, is, in all probability, to be sought for in the primary inter- cellular substance. Not only do the forms of the hollow fibrous reticulation, in other words, the capillary vascular rete {fig. 213), accord with those of the loose elastic tissue, and the primary inter- cellular net of the cartilages which is afterwards changed into spongy bone {fig. 60) ; but in number and dimensions the vascular meshes seem also to agree with those of the cells secondarily evolved 210 PROPER FIBROUS TISSUES. from parent cells, as we see them in the ossific cartilages.* That the vascular capillary rete, and likewise the elastic tissue, arise from hollow cells connected in the manner of a net (jride § 132), and originally produced in the intercellular sub- stance, is more probable on analogical grounds, than that the intercellular substance should, without further secondary cellular formation, become hollow. It must he allowed, however, that varicose enlarge- ments or spindle-shaped cells are very rarely seen in the course of the elastic fibres, or at the points of their inosculations, during the period of their de- velopement. An abundance of such enlargements and cells, nevertheless, is constantly observed in connexion with the yet imperfectly formed fibres of cellular tissue that are interspersed among those of the elastic tissue. PROPER FIBROUS TISSUES. § 213. The mode in which cells comport them- selves and combine so as to form cellular fibres has been already alluded to (§ 31, 84, 85, 87, and 131), and in the cellular tissue of certain parts the de- velopement goes no farther than as it has been heretofore described. In others, the intercellular or connecting fibrils undergo elongation, the fusi- form cells disappear, and leave proportionately long fibres behind, which are either, 1st solid, and (a) * See farther on this subject in the Section that treats of Vessels. For additional information on the Elastic Tissue, see Eulenberg’s “ Diss. de Tela Elastica.” 4to. Berlin, 1836 ; Muller’s “ Physiology Schwann’s “ Mikroscopische Untersu- chungen;” and Valentin’s “ Repertorium.” CELLULAR SUBSTANCE. 211 flat, (5) prismatic, or (c) cylindrical ; or, 2d, tubu- lar or hollow and containing fluid. These fibres either lie parallel, near to one another, and form bundles or fasciculi, or they cross and interlace singly or in fasciculi, and so form simpler or more complicated textures. The cylindrical solid fibres are met with in the greater number of the soft parts of the human and animal body, either as principal or as subordinate constituent elements. With some slight modification in diameter, density, elasticity, colour, &c., they form constituents of very different systems. They exist, for example, in the fibres of the cellular substance, in those of tendons, ligaments, fibro-cartilages, contractile tis- sues, and muscles, which all, — in form, properties, composition and destination, — constitute different tissues. Cellular Substance — Cellular Membrane. § 214*. By cellular substance we understand the matter of which the fibres of the cellular tissues con- sist ; by cellular tissue , the various compounds that result from the crossing or intertexture of these fibres. The structure, which is commonly called cellular substance, is an extremely compound body, and besides proper cellular fibres contains blood and lymphatic vessels, serous fluids, blood and lymph, fat, nerves, &c. Cellular substance is a soft, moist, glutinous, elastic, white or grey coloured and very transparent material ; the peculiar delicacy of its elements gives it a certain resemblance to thick mucus. It forms cavities (arese, areol®) of various sizes, which are more or less completely 212 PROPER FIBROUS TISSUES. filled with serum or fat. It seems to possess a certain degree of organic contractility, i. e. an in- herent power, on the application of certain stimuli, of shrinking in bulk : it has, however, little ordinary sensibility. Delicate reticulations of blood-vessels and lymphatics extend in all directions and in great abundance betwixt its fibres and laminae ; it is therefore, upon occasion, apt to increase greatly in quantity, and is readily reproduced.* The branches of nerves which are visible in the cellular substance by the naked eye do not belong to it, hut merely pass through it towards other organs. In consequence of the delicacy of its elements it possesses considerable powers of adhesive and capil- lary attraction, so that it is often seen to become rapidly and greatly distended with watery fluids from neighbouring parts. Its meshes and areola) are more or less connected through the entire body, so that air or watery fluid permeates it readily, the watery fluid by reason of its specific gravity falling down and infiltrating the most depending parts. * After the cellular tissue has been completely destroyed it is generally not reproduced. Witness the adhesion, as it is termed, of the scars of old deep ulcers to bones, a circumstance which is often considered as a sufficient cause for the rejection of other- wise eligible recruits for the army ; and every one is acquainted with the depressed cicatrices, where there is a want of subjacent cellular tissue, which follow various sores, particularly those in which there has been sloughing of the cellular substance. Independently of ulcers, the cellular substance of some parts, as of the legs, appears to be liable to atrophy, so that the limbs become hide-bound. — See Edin. Med. and Surg. Journ. vol. xlvi. p. 308. — G. G. CELLULAR SUBSTANCE. 213 § 215. The elements of the cellular tissues are the fibres of the cellular substance, and present themselves in the guise of simple cellular fibres and perfectly rounded bands. The former constitute an extremely soft mucus-like cellular tissue ; the latter a stronger fibrous cellular tissue. As these different kinds of cellular tissue serve different pur- poses, we distinguish, 1st, the fibrous or varicose from, 2d, the fascicular cellular tissue. The rela- tions of the cellular tissue to the other tissues, to the different organs and systems, affords the basis of another subdivision ; viz. into 1st, investing and connecting cellular tissue ; and 2d, intimate or component cellular tissue. Microscopic Examination of Cellular Substance . § 216. The perfectly developed cellular sub- stance, consists of extremely fine and transparent, smooth, soft but tough, even, generally cylindrical fibres, with pale, delicate bounding lines, from T-§Vo to Txo-o of a Paris line in diameter, and which rarely run singly, but commonly in fasciculi, in wavy or sinuous lines ( fig . 19). It forms every variety of fibrous compound and tissue, viz. 1st. Single fibres traversing other tissues (fig. 73, e). 2d. Parallel fibres running either together and in contact, or separated by a gelatiniform inter- posed substance (fig. 194). 3d. Fibres united into flat cords, running parallel and close to one another, and either straight or sinuous (fig. 195, and fig. 19). 214 PROPER FIBROUS TISSUES. 4th. Simple parallel, and multilamellar parallel Membrane — composed of fibres running parallel and close to one another in the same plane, in one or in several strata {fig. 49, A, and fig. 200). The dense serous and synovial membranes, and the dense cellular sheaths of the firm nervous fasciculi, for instance {fig. 88, 9), belong to this category. 5th. Tissues of Cellular Substance — {fig. 49, B, and fig. 197)> composed by the interlacement and irregular crossings of single fibres. This tissue is met with between the fine layers of other tissues, and also in the most delicate portions of the serous membranes. 6th. Fibrous Net of Cellular Substance. — Iso- lated parallel fibres crossing and interlacing ob- liquely with one another {fig. 198). It occurs, like the simple cellular fibrous tissue, amidst finely stra- tified tissues, and as an envelope, of the ganglionic globules, for instance {fig. 89, 6). 7th. Fibrous Grating of Cellular Substance. — Isolated fibres crossed or interwoven at right angles {fig. 199). This occurs along with the fibrous rete and the irregular fibrous texture. 8 th. Tissue of Cords and Fasciculi of Cellular Substance A tissue composed of bundles or cords {fig. 50). It occurs in lax serous membranes, in the omenta, &c. The tissues made up of bundles and cords ex- hibit all the varieties of tissue formed by the simple fibres above enumerated, but it is unnecessary to specify them. § 217. The fibrous cellular substance frequently presents itself mingled with cells, nuclei, &c. CELLULAR SUBSTANCE. 21 5 Investing Cellular Substance. § 218. The investing and uniting cellular sub- stance, or the isolating superperipheral cellular tissue, covers the superficies of the greater number of single organs, which it isolates and yet connects, and the interspaces of which it fills up, smoothing in- equalities, and giving roundness and symmetry of form. It is a material of this kind that connects the skin with the subjacent parts, — the subcutaneous cellular tissue ; that contains the serous fluid which belongs to it (§ 17), and the subcutaneous fat, — fat vesicles and fat cells, which constitute something like one-twentieth of the whole weight of the body (§ 133). It forms universally larger and smaller serous cavities — arese, areolae. Cellular Substance entering into the Composition of other Tissues. § 219. The proper constituent matter or paren- chyma of organs is invariably intermingled with more or less of cellular substance, which, indeed, forms an essential element in their constitution, connecting the several particles together into a whole — the glomeruli of glandular structures into glands ; the primary muscular fibres and bundles into muscles ; * the primary nervous tubuli into nerves, &c. * There does not appear to be any cellular tissue between the muscular fascicles of the heart. At least, after several observa- tions made especially with a view to this point, it appeared to me that the fleshy part of the heart was entirely made up of its 216 PROPER FIBROUS TISSUES. Fibres of the Cellular Substance , Varicose Cellular Substance. § 220. The cellular fibre (§ 82 — 86), is the transition form of the cell into the filament. The fibre of the cellular substance is not, however, in every case a temporary or convertible element of this kind ; it often remains stationary at this stage of its evolution, so that some tissues or parts of tissues, consist, in great measure, of a structure of this kind. It forms, for example, a delicate envelope around the finer vessels {fig. 102, c, c), and around the soft nerves {fig. 1 63, c, d). With the final subdivisions of these organs, the fibres of the cel- lular substance quit them, and form a particular rete within their meshes {fig. 106, c, c). Fibres of this kind are encountered in almost all the tissues, either as a soft matrix, or as a delicate investing and connecting medium. Membranes of Cellular Substance. § 221. Membranes composed of cellular sub- stance are extensively disseminated through the body. They consist either of fibres densely com- pacted, or of tissues of these, either by themselves, or mingled with the fibres of the cellular substance. To this category belong the serous and synovial sacs. peculiar muscular fibres, without visible intermixture of any other tissue whatever. See “ Observations on the Muscular Fibre of the CEsophagus and Heart in some of the Mammalia.” — Proc. Zool. Soc. No. LXXXI. Sept. 1839. — G. G. SEROUS AND SYNOVIAL MEMBRANES. 217 1. Serous Membranes. § 222. These form shut sacs, lining all the in- ternal close cavities of the body, and investing in uninterrupted continuity the organs included within them. The free surface is covered with a tessellated epithelium, which in the ventricles of the brain alone presents cilise. The following are the mem- branes which are accounted serous : — The inner lamina of the dura mater of the brain and spinal cord ; the tunica arachnoidea of the same parts ; the pia mater or vascular membrane of the same parts, the lining membrane of the ven- tricles included ; the pleurae ; the pericardium ; the peritoneum, and its process the tunica vaginalis testis ; in the foetus, the amnion. The allantois seems to stand in the middle between the serous and the mucous membranes ; it is, however, an offset from a mucous membrane, the bladder of the foetus. The great serous sacs now enumerated agree essentially in structure and function with the smaller cavities of the loose investing or interstitial cellular substance, and only differ from these in their greater size, and in having their free surfaces overspread with a tessellated epithelium. The free surface is always smooth and polished, and lubricated by a serous fluid, by which all fric- tion between contiguous parts, and the coalition of these with one another are prevented. 2. Synovial Membranes. § 223. The synovial, like the serous membranes form shut sacs, and perform similar offices. They 218 PROPER FIBROUS TISSUES, are distinguished from these principally in their composition of several layers of immediately con- nected cellular filaments, and in their transudation of a serous fluid that is thicker and much richer in albumen than ordinary serum ; this is the synovia or joint oil, the necessity for the greater consistency of which is obvious. The synovial sacs either indue and close in the cartilage-covered ends of bones, when they are called articular synovial capsules , or they lie as simple bladders between tendons and projecting parts of bones, between muscles, and even between the skin and subjacent hard parts, when they are entitled bur see mucosce. All the tendons, too, that pursue their course to their points of attachment through long grooves of bones, or that pass round pro- minent parts of these as a cord does over a pulley, are provided with elongated synovial sacs, denomi- nated synovial sheaths. § 224 a. Articular Capsules. — Suppose a sphe- rical shut synovial sac to be pushed between the articular extremities of two bones, and to cohere with the entire cartilaginous surface of each to the very edges ; suppose the bones now approximated till the inner aspects of the synovial investment of the cartilages met, and the sac to be partially filled with synovia, the outer free portion of the synovial sac would then surround the joint like a girdle. Let this free girdle be farther supposed to be covered externally with a fine tendinous or liga- mentous membrane of corresponding size and form, and this to adhere by its edges to the periosteum in the circle of the articular cartilages, and a complete SYNOVIAL MEMBRANES. 219 idea will be obtained of an articular capsule. It is evident, therefore, that the articular cartilages are never immediately in contact, but that the inner smooth surface of the synovial membrane, separated by a thin stratum of synovia, is opposed to itself, an arrangement by which motion is greatly facili- tated, and the cartilages are protected from injury so long as the lubricating fluid is poured out in sufficient quantity and of proper quality. The outer fibrous or ligamentous girdle strengthens the free circular portion of the capsule. As the arti- cular capsules are completely closed, and the air of the atmosphere can in no way enter them, an ex- tremity, the muscles of which were completely re- laxed, would not fall away from the fixed part with which it was articulated, — the anterior extremity, for instance, from the glenoid cavity of the scapula, — so long as the weight of the extremity or the dissevering force did not exceed a certain amount, easily deter- minable and bearing relation to the extent of the articular surfaces.* Synovial capsules are frequently surrounded with a larger or smaller quantity of a yellow-coloured fat. The synovia is a viscid stringy fluid, per- fectly adapted to lubricate opposed surfaces. It * This of course results from the pressure of the atmo- sphere, which acts with a force equal to fifteen pounds upon every square inch of surface. Suppose the diameter of two contingent articular cartilages to be = 2 in. and the surface therefore to be = 2*96 square inches ; then under a mean baro- metric pressure of 29 inches, a power = 2-96 x 15 = 44*4 lbs. would be required to separate the articular head from the socket. 220 PROPER FIBROUS TISSUES. consists of serum with from six to ten per cent of additional albumen. It shews alkaline reaction. § 225. b. Synovial Sheaths of Tendons. — When- ever tendons play upon bones as cords do upon pullies, they are found provided with a double syno- vial sheath, being inclosed immediately within a synovial tube which is then reflected upon itself, so as to line the groove within which the motion takes place, in the same manner as the pleura and peri- toneum are reflected around the various viscera of the thorax and abdomen. These synovial sheaths are so loose at the extremities as to oppose no im- pediment to the freest motions. They are bedewed with a synovial fluid of the same nature as that of the articulations. § 226. c. Articular Bur see. — These are saccu- late or bladder-like synovial membranes, which commonly occur in the vicinity of joints and points of attachment of tendons, being placed betwixt these and a cartilage-covered and generally projecting portion of the bone. They contain the same kind of synovia as the articular capsules, and serve to facilitate motion and to spare the tendons when they play over elevations of bones. § 227. d. Subcutaneous Bur see In those places where the skin passes immediately over pro- jecting points of bone, as the elbow, tuberosity of the tibia, &c., an interposed bursa is always found, which facilitates the gliding of the integument over the hard projection, and also serves as a pad or cushion to diffuse the pressure. § 228. To the membranes composed of codlular substance appertain the cellular sheaths of the mus- TENDON. 221 cles, the outer coats of the blood and lymph vessels, and of the ducts of glands ; the inner coat also of the blood-vessels and lymphatics comes under the same head, unless it be assigned to the peculiar class of serous tissues, inasmuch as it is free, forms a closed, however much elongated and extensively branched cavity, and is covered with a tessellated epithelium. § 229. The cellular substance of the foetus, which consists, in great part, of cellular fibres, yields no gelatine by boiling, like the cellular sub- stance of older animals, and Schwann has observed that it is only the interjacent cytoblastema or hyaline substance that is dissolved in boiling water, not the cellular fibres themselves. This observation re- minds us of the insolubility of the foetal blood-disc by acetic acid. The division of the cellular fibre into a plurality of fibrils, which Schwann regards as constant, I have myself seen so seldom distinctly, that I am forced to look upon it as among the number of varieties. TENDON. Tendinous Fibre. § 230. The tendinous fibre is distinguished from the cellular fibre only by greater consistency and rigidity, and, in connexion with these qualities, by the maintenance of its natural sinuosities and crispings, by its greater degree of opacity and of regularity in its course, and the silky appearance which ensues from this ; farther, by a more invariable parallelism of the fibres to one another, upon which depends the pearly lustre of tendons. 222 PROPER FIBROUS TISSUES. The tendons have very minute blood-vessels,* which course between and parallel with the fibrous bundles, forming a wide-meshed rete. Tendons seem to have but a very limited supply of nerves. § 231. The tendons in the foetus are formed at even an earlier period than the cellular substance ; but in the same manner as it, the cellular fibres destined to form tendons collecting into rounded bundles soon after their formation. At first they are more transparent and of a dull grey, not glisten- ing like silk or mother of pearl. Even in the foetus the fibres of tendon are less separated by any inter- vening or connecting matter than the fibres of the cellular substance ; they are, therefore, more imme- diately and intimately in contact. From the one to the other, however, there is frequently a gradual transition to be observed, so that even in the adult doubtful intermediate forms of every degree of proximity to the one or the other are encountered. In the long tendons and firm tendinous membranes or aponeuroses, the fibres are straighter than else- where even in the foetus, hut in other places they are more plentifully mixed with cellular substance and more sinuous {fig. 31, b, c ). § 232, Chemical Examination of Tendinous Fibre. — Chemically considered, the tendons hear a * Some observations on the Blood-vessels of Tendinous Tissue have recently been made by Mr. Paget. — See Lond. Med. Gazette , vol. xxiv. p. 562. In the museum at St. Bartholomew’s Hospital there is an excellent injection of these vessels made many years ago with mercury by Mr. Wormald ; and Professor Sharpey shewed me some injections of the vessels of tendon when he was engaged as a Lecturer on Anatomy at Edinburgh. — G. G. TENDONS. 223 strong' analogy to the cellular substance. Those of the foetus yield little gelatine, whilst those of the adult are entirely dissolved into gelatine by boiling. They contain about 60 per cent of water, and when dry are brown, transparent, and more brittle than dry elastic tissue. T endinous Tissue. § 233. The tendinous fibre unites in general into bundles and cords, and forms fascicular tissues more frequently than fibrous tissues. The crossings of fasciculi are more readily seen in tendons than in formations of the cellular substance, in conse- quence of their higher reflecting power. In the long tendons the fibres lie parallel ; in the ten- dinous sheaths or aponeuroses, the fibres in bundles are mostly crossed and intricated. The tendinous tissue forms, 1st, Tendons of muscles, and these are either («) long and rounded, — proper tendons or sinews which belong mostly to the extremities ; or (6) broad and membraniform, — tendinous expan- sions, aponeuroses; 2d, Tendinous sheaths or fascia; and 3d, Fibrous membranes, and tendinous bands or ligaments. Long Tendons, Sinews. § 234. The tendons are the fibrous tissues con- nected with muscles, which generally serve them as means of origin and insertion, though in many cases the tendons run through or along the entire course of muscles. In the recent state they are sericeous or silky, of a bluish, yellowish, or reddish white, iridescent, extremely strong, but very little 224 PROPER FIBROUS TISSUES. elastic ; their fibres are generally parallel to the axis of the muscle ; in the penniform and semi-penniform muscles they run obliquely ; in form they are cylindrical or flat in different degrees, and conical on the muscles ; where they pass over hones or hard parts they are defended by synovial sheaths or bursae ; when they pass around a projecting process of bone, as a trochlea, they are sometimes seen con- verted into a substance having the texture and appearance of fibrous cartilage : in such situations they are always bound down and confined in their places by tendinous or ligamentous sheaths. Where the tendon meets the muscle, the primary muscular bundle is conically pointed, and the fine tendinous fibres arise from the entire cone (Jig- 31, a, 1). At the point where the tendon is attached to the bone, it is generally somewhat expanded ; the immediate attachment is the periosteum. Tendons, along with bones, cartilages, liga- ments, &c., belong to the passive organs of motion, and serve as admirable means of transmitting the inherent contractile powers of the muscles to a distance. The aponeuroses or tendinous sheaths again supply points of origin to the long tendons and muscular fibres, and, at the same time, bind down in their places and isolate the bellies of muscles and the tendons that proceed from them. Tendinous Expansions ; Aponeuroses ; Fasciae. § 235. The membraniform tendons or aponeu- roses often form the tendinous continuations of flat or membraniform muscles, and cover at once and TENDINOUS SHEATHS. 225 enclose other organs. They are either entirely tendinous, and their fasciculi run in one and the same direction, — the tendons of the external and internal oblique muscles of the abdomen, for ex- ample ; or the component fasciculi cross in different senses, — the tendinous portion of the diaphragm, for instance ; or, otherwise, they contain or are mixed with elastic tissue, — the aponeurosis of the external oblique, to wit. These tendinous expan- sions are pierced in numerous places by vessels and nerves. They serve, like the cordiform tendons of the long muscles, for the transmission of motion ; they assist in supporting the organs they surround, — the abdominal viscera, in particular, and compress these under the contractions of the appertaining muscles, by which they become powerful means aiding in many important processes. Tendinous Muscular Sheaths. § 236. Over the muscular sheaths of cellular substance, especially in the extremities, we find particular tendinous sheaths which surround the individual muscles in the shape of dense networks of fibrous fasciculi, and externally compose a general sheath including the muscles of the entire ex- tremity. The fascia) of the fore-arm, thigh, and leg, afford examples of this structure. These fibrous sheaths supply points of origin to the muscles, keep them in their places, and support them in their more violent exertions. With a view of renderino- these sheaths tense we even see particular muscles either attached to them entirely or sending off Q 226 PROPER FIBROUS TISSUES. tendinous processes to them : the great fascia of the thigh has its tensor muscle ; the sheath of the fore-arm has the strong offset from the biceps brachialis to brace it up. These tendinous sheaths are also attached to the hones, and sometimes they pass over into tendons and aponeuroses ; they likewise surround other organs, and attach and isolate these from neighbouring parts, — the muscles from one another, the muscles from blood-vessels, nerves, &c. Tendinous Membranes strengthening the Serous and Synovial Membranes. § 237. The free lying portions of the serous and synovial membranes are upon occasion supported and strengthened by means of fine tendinous expan- sions, which generally consist of a delicate reticula- tion of fibrous bundles, so intimately connected with the membranes that they are often scarcely to be separated from them. The outer layers of the pericardium, of the articular capsules and tendinous sheaths, of the linea alba abdominis, which is re- markably developed in the horse, are examples of the structure in question. Peculiar Fibrous Membranes. § 238. Different organs are surrounded by tough membranes, generally composed of an admixture of tendinous fibres and elastic tissue, and having, con- sequently, a pale yellow tint, and little or none of the pearly lustre of tendon. Sometimes the invest- ment seems to consist of tendinous fibres entirely, LIGAMENTS. 227 and then it shews the nacreous lustre ; though in other instances, the composition being the same, but the intrication of fibres greater, it is dull and lustreless. Of this description are the fibrous mem- branes that surround the erectile organs, at the same time that they penetrate their substance in all directions as a powerful network. We have examples of the structure in the fibrous membrane ‘ of the penis, clitoris, and spleen. The breast in the human female, and the udder and dug in the lower animal are also surrounded by a network, more or less close, of the same tissue, connected with the investing fibrous membrane, and suspend- ing the erectile vessels in its meshes. The exces- sive dilatation of many organs is guarded against by strong investing proper membranes. The dura mater, the tunica albuginea testis et ovarii, the tunica sclerotica oculi, the periosteum and the ligamentous articular sheaths, which in many places surround such compound articulations as those of the wrist and tarsus, belong to this category. These fibrous membranes form a medium of transition to the ligaments properly so called. Fibrous Bands ; Ligaments. § 239- The fibrous bands or ligaments of the articulations, and of the cartilaginous and fibro- cartilaginous junctures of the bones are, on the one hand, closely allied to tendons ; on the other, to fibro-cartilages : they consist of fibres stronger, more disposed to crisp, and which, though connected parallel with each other, shew less of the silky or pearly lustre than tendons ; the ligaments are also 228 PROPER FIBROUS SHEATHS. of a yellower hue than the tendons. They are partly to be viewed, like the tendinous corroborating sheaths of the articular capsules, as extensions or productions of the periosteum over joints ; some, however, are actually included in the fibrous cap- sule, the transverse ligaments of the tarsus and carpus, for example, the round ligament of the hip, and the crucial ligaments of the knee joint ; the latter proceed from one bone to another athwart the joint, and are surrounded by a tubular production of the synovial capsule. Besides the round and cruciate ligaments just mentioned, we have lateral ligaments, straight or perpendicular and oblique ligaments, annular ligaments, trochlear ligaments, &c., particularised. In shape they are cylindrical, prismatic or flat, elongated or annular. The round ligament of the hip-joint is cylindri- cal, and runs from the middle of the lower edge of the acetabulum to the pit in the head of the thigh bone. The crucial ligaments of the knee belong to the prismatic order, and connect the femur with the tibia in the middle of their opposed articular sur- faces, crossing each other at an acute angle. The lateral ligaments are for the most part flat, and connect the bones externally, and in such a way that hut a very limited degree of motion is admis- sible save in one direction ; general investing liga- ments, as those of the carpus and tarsus, only allow a slight amount of gliding of the articular surfaces one upon the other ; the annular ligaments surround the neck of a bone so as to form a kind of pivot- joint. The ligaments are in a great measure convert- FIBRO-CARTILAGE CONTRACTILE TISSUE. 229 ible into gelatine by boiling, like the tendons ; but they dissolve less readily than these. They are among the toughest, the strongest structures in the body ; they are the rather adapted for the purposes they serve as they possess some slight elasticity ; they are considerably more elastic than tendons. Fibrous or Fibro-cartilage. § 210. Fibro-cartilage, when its texture and general properties are considered, seems to occupy a place intermediate between cartilage and liga- ment. It consists in general of dense intercrossing fibres {fig. 53, A), but in some cases there is be- yond all doubt a considerable intermixture of elastic tissue, when the structure assimilates itself with reticular cartilage. It is highly elastic, of a yellowish white colour, and in general obviously fibrous. It forms the intermediate substance in all the articula- tions by synchondrosis, uniting the bones without the intervention of capsules by means of a succession of concentric laminae of fibres crossing one another obliquely in opposite directions. All the vertebrae, save the atlas, are connected in this way, as are also the bones of the pelvis with the sacrum and with one another. CONTRACTILE FIBRE — CONTRACTILE TISSUE. § 241. Beneath the skin, especially in those places where, under the influence of cold and other peculiar stimuli, a notable corrugation and thickening are obvious, certain fibres may be distinguished, differ- ent from the round fibres hitherto described, in as much as they are of somewhat greater diameter, of 230 PROPER FIBROUS TISSUES. a redder colour, and possess a peculiar kind of transparency. These fibres are, however, met with not only immediately beneath the skin, but in its substance, and either singly or united into cords or bundles. They run more or less parallel and near to one another {gfig. 73, a , b, from the scrotum, where they are interwoven with transverse fibres and bundles of cellular substance, c); or they form plexuses which resemble the terminal plexuses of the nerves {Jig. 7 1 > «, and fig. 7 % «), with this difference, that the individual fibres interlace and amalgamate, the several bundles not merely inter- changing primary fibres without any real blending as the nerves do {figs. 91, 93, and 106). The inherent contractile power of these fibres and their general structure place them as transition- forms from the passive round fibre to the active fibre of muscle. In the skin of the hog they measure from the T|^th to the ~-th 0f a paris line in diameter. The contractile tissue, now alluded to, on the application of cold, and under the influence of mental emotions, — rage, terror, &c., produces the appearance called goose-flesh, and causes the hair to become erected. In some limited portions of the integument the corrugation effected is still more remarkable ; the nipple, for instance, becomes hard and in some sort erected by its means ; the scrotum too becomes as hard as a ball, and greatly shrunk in size, by which the testes are forced up towards the inguinal rings, and as actively compressed as they are by the cremaster muscles. This con- tractile tissue enters as an element into the constitu- MUSCLE. 231 tion of the penis and clitoris, probably also of the blood and lymph-vessels, and of the excretory ducts of glands. The motions of the iris, producing con- traction and dilatation of the pupil, seem likewise to depend on the agency of contractile tissue, light acting as the appropriate stimulus here ; hut this is a point upon which information is attainable with greater difficulty than as regards the common integument. MUSCLE MUSCULAR TISSUE. § 242. The flesh or muscles of animals are of a pale or darker red colour, and consist of a multitude of fibres and fasciculi of fibres, intimately connected and running parallel to one another. Muscles are the instruments of active motion, voluntary as well as involuntary, through the whole series of the animal creation, and this they are in consequence of their inherent power of alternate contraction and relaxation. As means of voluntary motion we see the muscles arranged around the trunk and ex- tremities, which they use as levers for the execution of the behests of the will. As means of involuntary motion we see them forming the middle tunic or the mass of various hollow or tubular organs, the dia- meters of which they diminish by contracting, and which by relaxing they suffer again to be distended. The muscles are generally divided into (1) or- ganic, (2) animal, and (3) mixed ; in other words, into such as belong to the organic life, such as be- long to the animal life, and such as are of a mixed nature. The muscles of the organic life contract and do their office involuntarily and without the 232 PROPER FIBROUS TISSUES. consciousness of the animal : the muscular substance of the heart, the muscular parietes of the stomach and bowels, are muscles of the organic life. Muscles of the animal life are under the control of the will and only act to execute its purposes : the muscles of the extremities all belong to the animal life. Muscles having a mixed character execute certain motions involuntarily and unconsciously to the in- dividual, and yet are under the influence of the will to perform motions for other purposes, or to execute the same motions more rapidly or more slowly ; of this kind are the muscles of respiration, which carry on the process of breathing during sleep, that produce involuntary sneezing, coughing, crying, &c., and that yet under the influence of the will elicit the voice, &c. The muscles are very plentifully supplied with nerves of motion, and but scantily with nerves of sensation ; they are therefore highly irritable, but by no means very sensitive. Organic or Involuntary Muscles. § 243. The muscles of organic life are in con- nexion with the organic or ganglionic system of nerves, and are, therefore, independently of con- sciousness and will, excited to certain determinate actions, which here are strictly rhythmical and interchanged with cessations from action ; they are spasmodic in some sort or irregular in their periods of activity and relaxation. The muscles of this class are for the most part pale in colour, finely fibrous, soft, transparent, deeply situated in the body, and moderately supplied with soft, greyish- coloured nerves, mostly of the motory order, and with blood- ORGANIC MUSCLE. 233 vessels, both of these coursing in general between the fibres and fasciculi that compose them. The organic muscles are more susceptible of mechanical than of chemical stimuli, and are not connected with tendons like the muscles of the animal life. § 244. Examined microscopically, the organic muscles are found in general to consist of delicate yellowish red coloured transparent fibres, with very faint boundaries, which, like the round fibres especially, though singly cylindrical, are flat or pris- matic when united into bundles, the pressure of the several fibres giving- them this figure. The fibres seldom run stretched out, and united into round bundles as in Jig. J5 A, a, a ; they are far more com- monly bent sinuously (B), or are even crimped (c) and combined into flat cords. In a higher degree of rigidity they are often irregular and shortly bent, by which they acquire the peculiar angular charac- ter which H. R. Ficinus* has so faithfully repre- sented in his figures. The fibres and bundles open and close under the mucous membranes in the manner of nervous plexuses, and form meshes in which mucous glands lie imbedded, or they surround these like loops. The muscular bundles lying in the same plane form muscular membranes, which are * “Diss. de Fibrag Muscularis Forma et Struetura.” 4to. Lips. 1836. Dr. Baly has given some good observations on the organic muscular fibre, and an accurate delineation of the corpuscles observable in the flat fibres or filaments. See Translation of Muller’s “Physiology,” 1838, plate 2, fig. 9. The corpuscles, according to my observations, are often absent, though the riband-like filaments may be very distinct. — See Proc. Zool. Soc., Sept. 10, 1839. — G. G. 234 PROPER FIBROUS TISSUES. disposed one over the other in two or three layers, the component bundles of each always crossing those of the other obliquely or at right angles, thus form- ing networks or gratings {fig. 85, and 76, A). In this manner appear for the most part the fibres of the muscular coat of the oesophagus, near the stomach ; of the stomach itself, and the intestinal canal, with its immediately derived ducts, the hepatic and pancreatic ducts ; of the urinary bladder and the ureters ; of the vesiculse seminales and vasa defer- entia; of the trachea and bronchi ; and of the middle coat of the veins and lymphatics. Frequently, however, the fibres are less divided and the fasciculi more distinctly granular {fig. 7 6, B) ; sometimes, indeed, they are decidedly granular, as in the uterus of the cow {fig. 74) : from the ends of the tom granular fibrous bundle (A) project fibres of cellular substance, which, running betwixt the granular fibres, appear to be connected with the granules ; at least, the granules remain hanging to the apparently branched fibres after operating on the bundles by alternately squirting water on them and pressing them gently {fig. 74, B).* Although the organic muscular fibres in general appear so regularly granular (§ 251), this is seldom the case with the fibres of vessels which, as Professor Valentin t has already shewn, resemble the larger examples of the contractile round fibre so much, that it is still doubtful whether they ought not rather * This appearance of the uterine muscles I have, indeed, only seen very distinctly once, but then it was in sections from different parts of the organ. t “ Repertorium,” 1837. S. 242. PASSAGE OF ORGANIC INTO ANIMAL MUSCLE. 235 to be assigned to the contractile than to the proper muscular tissue. § 245. An isolated, azygous, organic muscle, partly covered by the skin only, is found in the solidungula under the urethra. This retractor of the penis possesses the precise texture and colour of the organic muscles : it is a prolongation of the muscles of the rectum to the glans penis. Passage of the Organic into the Animal Muscles. § 246. No voluntary muscle without transverse streaks is known;* but some muscles that have transverse striae, nevertheless, from standing in a certain relationship to the animal as well as the organic system, assimilate in their mode of action with the involuntary muscles. To this head belong the muscular substance of the heart and that of the oesophagus near to its ventricular end.t The deep * Many fibres of voluntary muscle are without these streaks. Such fibres appear to be composed simply of irregular granular matter inclosed in a sheath (sar colemma) without the least ap- pearance of primitive fibrils. In the pectoral muscle of the long- eared bat ( Plecotus auritus, Geoff.), examined immediately after death, almost all the fibres were of this character. They mea- sured from -g-g-g-th to y-fyst of an English inch in diameter. — G. G. f The muscular fibre of animal life invests the gullet much nearer to the stomach in many brutes than in the human subject ; and there is also a remarkable difference in this respect in several of the mammalia. In some of the rodentia, and in the sloth bear ( Ursus labiatus, Blainv.), the muscular fibre of animal life extends to the cardia, and in some mammals may be found beyond the termination of the gullet. In the quadrumana, in the horse, in the lion, and many other species of felis, the muscular fibre of animal life does not extend nearly to the end of the gullet. The subject is deserving of further inquiry. 236 PROPER FIBROUS TISSUES. red muscles of the heart consist of fine transversely streaked, and often waved, primary fasciculi, from the lixoth to the sVth of a line in diameter, which divide again and again like the prongs of a fork, and combine in the manner of a net {fig. 84). These muscular fasciculi contract and relax without intermission, rhythmically and powerfully, from the commencement of life in the embryo, to its end, at the age it may be of a hundred years, forcing the Professor Muller assures us that “the third act of deglutition is quite involuntary, being performed by the muscular fibres of the oesophagus, which are not in the slightest degree capable of voluntary motion.” However true this may be as regards man, it is probably different in those animals which have the entire muscular sheath of the gullet composed of fibres identical in all respects with the fibres of the known muscles of voluntary motion. The muscular structure of the heart appears to me to be altogether peculiar ; not to mention other points, the compara- tively small size of its primary fascicles, and the absence of in- tervening filaments of cellular tissue, serve to distinguish the muscular fibres of the heart from the fibres of the muscles of voluntary motion. See “ Observations on the Muscular Fibres of the (Esophagus and Heart in some of the Mammalia.” — Pro- ceedings of the Zoological Society, part vii. p. 124, et seq. I subjoin from my notes measurements of the size of the primary fascicles of the heart in several mammals. Though the size of the fascicles differs considerably, it is uniformly smaller than that of the primary fascicles of the muscles of voluntary motion. But in very young animals this difference is often scarcely appreciable ; thus, in a kitten a few days old, the primary fascicles of the pectoral muscle were as small as those of the heart. The fascicles of the auricles were generally found to be much smaller than the fascicles of the ventricles; but there were some exceptions : in the bearded sheep ( OvisTragelaphus) and the fox, there was scarcely any difference in the size of the fascicles of the auricles and ventricles. The following measure- ments are expressed in fractions of an English inch ; the animals, PASSAGE OF ORGANIC INTO ANIMAL MUSCLE. 237 blood poured into the cavities of the heart in its determinate round, and proving the efficient cause of the pulse. The number of contractions of the heart in the adult human subject amounts, on an unless noted to the contrary, were adults which had been dead several hours before the hearts were examined : — Table shewing the Diameter of the Primary Fascicles in the Heart of some of the Mammalia. Name of Animal. Cercopithecusgriseo-viridis,Desm. Cercopithecus sabseus, Desm Cercopithecus iEthiops, Geoff. ... Macacus Rhesus, Desm Yespertilio noctula, Schreb Plecotus auritus, Geoff. Ursus labiatus, Blainv Canis Vulpes, Linn | Canisfamiliaris, Linn. (12 days old) Canis argentatus, Desm Felis Leo, Linn. (J-ds grown)... Felis concolor, Linn j Felis Leopardus, Linn Felis cervaria, Temm Felis Caracal, Gmel Lutra vulgaris, Erxl Equus Caballus, Linn Antilope Bubalis, Pall j Ovis Tragelaphus, Desm j Sciurus vulgaris, Linn Cavia Cobaya, Gmel j Lepus timidus, Linn Part from which Fasciculi were measured. Diameter of Fasciculi. Ventricles 1 T3 3 3 t0 TTj'oTt Ditto ditto ... ditto Ditto ditto ... ditto Ditto ditto ... ditto Ventricles TilO <1 _ 1 * * * 10 0 0 Right ventricle 1 16 017 _1 ••• 8(70 Left ventricle 1 2 0 0 77 ••• ToVff Ventricles and auricles j T. The nerves of the sympathetic or gan- glionic system are like the ganglia themselves, of a reddish grey colour, and transparent in a greater or less degree, and not symmetrical. The microscopic investigations of Retzius, J. Muller, and particularly Remak,* have recently shewn that the nerves of this system generally, contain an admixture of or- dinary nerves or nervous fibrils, which proceed, according to Valentin, t from the brain and spinal cord, and probably preside over the functions of the vascular system — circulation, nutrition, secretion, &c. These adventitious nerves are so little nerves * “ Obs. Anat. et Microscop, de Syst. Nervos. Structural’ 4to. Berl. 1838. f Valentin : “ De Functionibus Nervorum Cerebr. et Spinal.” 4to. Bernse, 1839. 256 TUBULAR TISSUES. of sensation, that they scarcely convey any but the most indistinct ideas of irritations impressed upon the vegetative organs. As the sympathetic nerves, besides the excitement of involuntary motions in the organic muscles, are intimately connected with the vascular functions, and always accompany the blood-vessels very closely, they are with great pro- priety named the organic or vascular nerves. Microscopic An alysis of Nerves. § 265. The nerves consist, in general, of a con- geries of delicate tubes, which, examined in an animal immediately after death, are found to be cylindrical and of like diameter, individually trans- parent, and in their interior to inclose a fluid which, however, speedily coagulates into a grumous, uni- formly and very finely granular mass, although the separation of the coagulum into a thicker and thin- ner portion would seem to indicate a difference in the nature of its constituents. The nervous fluid probably separates imperfectly into a hyaline sub- stance, which becomes grumous and finely granular in coagulating, and into a thick serum. The fine elementary tubes or primary fibres of the nerves, are connected by an amorphous matter, or by a more highly developed cellular substance into fas- ciculi and cords, and these involved in denser cel- lular sheaths constitute the nerves in the ordinary acceptation of that word. More particularly examined, with the assistance of high powers and artificial light, a more delicate investing membrane is discovered within the outer NERVE. 257 thicker and sharply defined one of each particular fibre. This fine membrane appears to he composed of, or at all events to be covered by, a ciliary epi- thelium, the cilite of which lie very obliquely and apparently in spiral lines upon its inner aspect { jig. 88, 4, a, b, and 5).# Soon after death the nervous tubes contract irregularly, probably in consequence of the unequal density of the contained fluid after its coagulation ; the tube then, from cylindrical and even, becomes alternately contracted and dilated in its course ( Jig. 88, 3). Such a moniliform state of the nervous fibres at their origin in the brain and spinal marrow would even seem to he the natural condition ; the knots or dilatations are certainly far more remark- able here than in the general course of the nerves. Immediately after death they present themselves in a cerebral nerve as they are represented in Jig. 89, 7 ; and in a spinal nerve as they are depicted Jig. 89, 8. Even after they have escaped from the spinal cord, the fibres are still somewhat varicose {fig. 89, 8, a , e) ; they only become regularly cylindrical when * If this structure be confirmed by the observations of others, the nerves would come to be ranked among the true vessels. The peculiar structure in question was first noted by Professor Valentin in a course of observations upon the nerves of living animals, which we had undertaken in common about a year ago. The object of the movement of the nervous fluid in the interiors of the tubes, supposing it to be continued back- wards from the ultimate loops, would be precisely that which is accomplished by the heart in regard to the blood — a constant, although perhaps, slow change of the contents of the nerves from the centre towards the periphery, and from the periphery towards the centre. S 258 TUBULAR TISSUES. they are surrounded by the firm sheath of the nerve at large. These roots, moreover, are finer and more transparent than the fibrils of the rest of the nerve, and they are severally provided with a delicate covering. In all probability two fibres of the roots of the nerves form a loop in the brain and spinal marrow as they do on the periphery. Here they are sur- rounded by the finest albuminous granules of the cineritious substance {fig. 89, 1), which, indeed, in some parts, seem to adhere to them like berries on a stalk {fig. 89, 7)* The radicles of the nerves, which in the brain and cord are separate and distinct at first, unite as they pass beyond the central organs into fine fasciculi, which in the first instance are surrounded by the pia mater, and by and bye, where the smaller bundles unite into larger, by processes of the dura mater ; as regards the spinal nerves, the fasciculi of the roots pierce the dura mater of the cord singly, and are then involved in common by a process from its outer layer. At the place where the process from the dura mater joins the nervous trunk which has now been formed, the fasciculi proceeding from the posterior columns of the spinal cord begin to cross and interlace, and form a ganglion, in which are included numerous isolated as well as clustered ganglionic globules, and from which also new fibres arise to swell the bulk of the future nerve of sensation, which is here finally completed in its structure {fig. 89, 2, 3, 4). The corresponding bundle, or nerve of motion con- stituted by the fasciculi which proceed from the anterior columns of the spinal cord, is intimately NERVE. 259 connected in its passage with idle ganglion of the nerve of sensation, but without mixing obviously with it. The sensitive and motory bundles now form a common cord, each of these bearing reference in point of size to the destination and functions of the nerve which then generally proceeds by the shortest route to the parts it supplies, dividing into smaller and smaller fasciculi as it advances these secondary bundles, consisting, of course, of sensory or motory primary fibres, or of a mixture of the two according as the parts to which they are finally distributed are organs of sensation or of motion, or contain both motory and sensitive structures in their composition. The most careful examination discovers no difference in the structure and appear- ance of the bundles and their fibres whether they he connected with sensation or motion. The continual divisions and subdivisions of the nerves imply a continually increasing expansion towards their peripheral extremities ; each trunk, in fact, just as in the case of the blood-vessels, comes to represent a cone, the basis of which lies in the periphery, the apex towards the centre. The cones thus formed blend in various ways with one another, as the functions of the organs comprehended within them require, as it were, different nervous mixtures, such as we may pre- sume could not have been conveniently formed at the commencement of the trunk. In the eye, for example, we see the peripheral expansions of many different nerves, in order to unite a variety of powers, and secure the requisite co-operation of the principal or more important nerves with others that 26 0 TUBULAR TISSUES. are only accessory : in the organ mentioned we have the involuntary motions of the iris united with the voluntary motions of the eyeball ; and then we have the special sense of sight associated with common sensation, with irritability, nutrition, and secretion. § 266. The nerves which proceed from different parts of the central system and unite in this way in their peripheral expansions generally combine in retes or networks, giving and receiving alternately bundles and isolated fibres from neighbouring branches ; these bundles and fibres, however, merely joining with each other and proceeding side by side, never anastomosing and blending into single trunks as vessels do when they meet ; the primary or ultimate fibres of nerves, in fact, only form loops or circles, they never end ( Jig . 104) ; the mutual interchange of bundles and single fibres is often extremely complicated, but no one is ever lost ; it either returns upon itself, or joins some neighbour- ing fibre or fasciculus, and so begins its backward course to the central system whence it had pro- ceeded. The reticular unions of the nerves are universally designated as plexuses, which are of different kinds: — 1st, Plexuses of the roots; 2d, Plexuses of the trunks ; 3d, Plexuses of the branches ; 4th, Ganglionic plexuses ; and 5th, Terminal or peripheral plexuses. 1. The root-plexus is a mingling of the roots of different nerves before or in connexion with the formation of nervous trunks ; e. g. the plexus between the facial and acoustic nerve. 2. The trunk-plexus is a mingling of the trunks of different nerves ; e. g. the axillary plexus. PERIPHERAL NERVES, 2Gl 3. The branch -plexus is a blending of the branches of nerves ; e. g. the facial with the tri- germinal. 4. The ganglionic plexus is mostly observed among the organic nerves, and is divided into (a) internal or cellular plexuses , in which the nervous bundles meeting in the ganglions open and make interchanges mutually of the primary fibres which inclose ganglionic cells {fg. 107) ; ( [b ) external ganglionic or radiated plexuses, which are radiated combinations of organic nervous trunks and branches by means of ganglia ; e. g. the solar plexus, the mesenteric plexus, the renal plexus, &c. 5. The terminal plexuses are formed by the finest and most delicate ultimate bundles, and occur of various degrees of complexity in the entire periphery of the nervous system. Those of the organic nerves are as yet but little known ; those of the voluntary muscles, however, have been fully examined {Jig. 91). The terminal plexuses of the nerves of touch and of common sensation are remarkably developed {Jigs. 93 and 94, upon a section, and 95 upon the surface of the corium). Peripheral Terminations or Expansions of the Nerves. § 267. From the ultimate peripheral plexuses of the nerves individual primary fibres at length take their departure and form terminal loops ; or, other- wise, the finest fasciculi and cords resolve them- selves into primary fibres which form the terminal loopings, these being always constituted by two primary fibres from the same or from different 262 TUBULAR TISSUES. fasciculi. Such final loopings present themselves wherever peripheral nervous influence or impressi- bility is manifested ; for the nervous workings in the various organs depend not upon the trunks, branches, ramuscles, or even the most delicate fasciculi ; hut upon these final loopings of the nerves, which are, therefore, the necessary media by which the motory nerves elicit motion, the sensory nerves convey sensation. The pain or im- pression produced in the point of the trunk of a nerve which is irritated, and which usually accords in kind with that which belongs to the peripheral expansion, depends, as my discovery has shewn, upon the presence of terminal loopings in the fasci- culi themselves (Jig. 162, bed, efg, him), — nervi nervorum, in short, which stand in the same rela- tion to the nerves as the vasa vasorum do to the larger blood-vessels. § 268. The final loops of the organic muscular nerves are still hut little known. Those of the animal muscular nerves have been more studied ; they are generally of considerable size : from a terminal fasciculus, which generally runs parallel with the muscular fasciculi, primary fibres proceed, and forming wide arches across the line of the muscular fasciculi, associate with another nearer or more distant nervous bundle and begin their back- ward course (fig. 91). According to Prevost and Dumas the muscular bundles can be seen bending during their contractions in considerable angles along the line of these nervous arches (§ 252). § 269. The final loops of the nerves of sensa- tion, those of touch in especial, arc less open than PERIPHERAL NERVES. 263 the final loops of the voluntary muscles {figs. 97 and 98). In those that surround and that pene- trate the bulbs of the hairs, the loops seem even to be completely, or all but completely, closed {fig. 91, h, h, c, c) ; those of the pulps of the teeth are also, according to Valentin, but very slightly open {fig. 105) ; and, like the loops in other situations, are formed now from primary fibres proceeding from and returning to the same bundle {fig. 98) ; now proceeding from one and returning to different and more distant bundles {figs. 92 and 97)* The final loopings in the less sensitive portions of the skin comport themselves like the associated capillary inosculations of the blood-vessels, which have long been familiarly known (compare figs. 97 ancl 98, with fig. 137 ? and fig. 92, e, with fig. 138) ; and where the final loops resolve themselves into many sub- ordinate or smaller ones by doublings and convolu- tions for the purpose of forming a multiplier for the peripheral neuro-electric function, as they do in the tactile papillae {fig. 9% e,fi; fig. 93, d, d, d ), the peripheral distribution of the capillaries will be found to be of the same description {figs. 138 and 139). The highly sensitive tactile papillae seem often to consist of a single greatly convoluted primary nervous fibre {fig. 99). Fusiform multi- pliers of the same kind are occasionally formed in the course of straight primary fibres {fig. 100). Several shortly convoluted terminal loops disposed like the segment of a sphere sometimes form the rosette-like nervous or tactile papillae which are exhibited in fig. 101. Between such tactile rosettes, or capitulate nervous papillae, we sometimes observe 2G4< TUBULAR TISSUES. simple loops included ; for example, in the finger of man {fig. 93, c, c). Organic or Ganglionic Nerves. § 270. The ganglionic nerves are called organic because of their obvious connexion with the organic or vegetative functions ; they are also sometimes spoken of as nerves of the vascular system, from their close alliance, not merely with the offices, but with the trunks and branches of the blood-vessels, very different from the cerebro-spinal nerves which only associate themselves with the ultimate inoscu- lations of the vascular system. It is possible that the persistent cellular fibres, which surround the oftentimes scantily distributed primary nervous fibres in relatively larger propor- tion {fig. 163) may serve as subordinate means of conducting the nervous influence ; at all events, that these peculiar cellular fibres may stand in closer relationship to the nervous system than the embryonic or transition form of cellular fibre which has the faculty of assuming other shapes, such as cellular membrane, tendon, &c. We, indeed, find that not only are the soft or organic nerves and the branches of vessels surrounded by these persistent cellular fibres {fig. 163), but that the primary nervous fibres are very constantly accompanied by them {fig. 102, c, c ; and fig. 103, d, d). The finest fasciculi of the animal nerves seem to be surrounded and accompanied in the same way ; the cellular fibres, according to Remak’s observations, first quit the nervous bundles when they proceed to GANGLIONIC CELLS. 265 form terminal plexuses, and may still be seen in the shape of retes within the meshes of these (Jig- 106). The ganglionic globules are further surrounded by the same form of cellular fibre in the ganglia them- selves (§ 271), as they are when they occur in the course of the ganglionic nerves. The nuclei of the peculiar cellular fibres in question are granular {fig- 102, d). The finer fasciculi of the nerves of sensation frequently open up in the manner exhibited in Jig. 90. The peripheral terminations of the nerves are peculiar in some of the special organs of sense ; for example, in the eyeball. Here the end of the optic nerve expands in the guise of a hollow hemi- sphere, and forms the retina which consists of two layers, viz. a granulated fibrous reticular layer, and a layer of dispersed granules. The olfactory nerve forms in the substance of the mucous membrane of the nostrils a flat, extremely delicate, and fine- meshed terminal plexus without any apparent final loopings of primary fibres. Ganglionic Globules or Cells ; Grey Nervous Substance ; Ganglia. § 271. In the grey matter of the brain and spinal marrow, intermixed with blood-vessels, albu- minous granules, grey organic or naked fibres, and nascent roots of nerves, which form the largest por- tion of the mass, we observe numbers of rounded, relatively large, granular cells, inclosing granular eccentric nuclei and nucleoli ; these are the gangli- onic cells or ganglionic globules {Jig. 89, 2, 3, 4). They are cither rounded, more frequently ovoidal 266 TUBULAR TISSUES. and ellipsoidal, or more rarely pyriform or fusiform in shape. They vary considerably in point of size, being to the blood-discs in the ratio of two, three, four, or five to one. They hear a strong resem- blance, as Valentin has remarked, to the unim- pregnated ova of the ovaries : the granular contents remind us of the yolk, the nucleus of the germinal vesicle, and the nucleolus of the germinal spot (the two last, like the cell, consist entirely of granules). They are immediately surrounded and connected by a tissue of organic fibres (§ 264,y?g\ 89> 5, a, a); and more than this, in ganglia they are included between the outgoing and incoming interlaced fibres of the white and grey nerves (fig. 107). The ganglionic globules are contained, 1st. In the grey central and cortical substance of the brain and spinal cord. 2d. In the trunks of nerves, viz. at the place of contact or of union between the root of the nerve of sensation and the corresponding root of the nerve of motion, as in the fifth cerebral and all the spinal nerves ; in the course of the grey organic nervous trunks — the sympathetics — either isolated and mixed with their substance, or collected into clusters without sensibly increasing their dia- meter. 3d. In the peculiar ganglia of the trunk and branches of the sympathetic nerve. § 272. Peripheral impressions are transmitted to the nearest ganglion with which the part of the periphery impressed is connected, and are received with or without consciousness, according as the receiving grey or ganglionic substance is contained in the brain or spinal marrow, or in one or other of the disseminated ganglia. From thence follows, in ORIGIN AND EVOLUTION OF NERVES. 267 a centrifugal direction, the nervous reaction which is proclaimed or manifested by motion — reflex motion, or by phenomena or actions of other kinds, either in the impressed periphery itself or in its neighbourhood, or in some more distant part only connected with that peculiarly impressed in virtue of the general association which makes one whole of the nervous system. Origin and Developement of the Nerves in the Embryo. § 273. In the embryo the nerves are found to arise essentially in the same manner as round filaments and the primary bundles of muscles. The embry- onic cell-substance arranges itself into cell-fibres, and from the very finely granular intercellular fila- ments, which are not yet white, but of a reddish grey and transparent, like Remak’s organic fibres, arise the primary fibres of the nerves. As was rightly observed by Schwann, the white colour of the nerves first appears when within the delicate boundary line a sharper contour is perceived, in- dicating the outer surface of the proper nervous tubulus or hollow filament, to the inside of which a fainter line is by and bye seen, announcing the inner aspect of the tubulus, as distinguished from its contents. Meantime the nuclei, which had at length been separated by considerable spaces, dis- appear. The delicate outer covering of the now completed nervous filament, however, still remains in the shape of a continuous pulpy substance, and is therefore to be regarded as the intercellular con- necting hyaline matter or cytoblastema, in which, 268 TUBULAR TISSUES. as between the fasciculi of the muscles, the cyto- blasts make their appearance, which then go on to be evolved into the cell -fibres and connecting cellular filaments of the nervous fasciculi, and which belong not to the nervous filaments but to the somewhat later formed derivatives from the cellular substance. Such is the view that has been taken by all observers of the mode of origin and formation of the nervous system betwixt its central and peripheral portions. But we have still to ask, in what manner the central and the peripheral portions of this great system originate and attain to their complete de- velopement? Here as elsewhere, doubtless, and particularly as regards the periphery, the terminal plexuses and loop -like bendings of the primary fibres must stand in a certain determinate relationship to the surrounding structures. § 274. As in every other particular organ and system of the body, wo observe diversity between the texture and general characters of the central, of the middle or transition, and of the peripheral or extreme portions of the nervous system. The peri- pheral parts of the vascular and nervous systems present too many points of analogy or rather iden- tity in their forms, to permit of any doubt being entertained as to the similarity of their mode of developement. The terminal plexuses of the nerves exhibit the same type in the particulars of relative size and arrangement of parts, as the arterial and venous networks ; the terminal loopings of the nerves have, in fact, capillary terminal nooses of the vascular periphery as regular attendants. We COMPOSITION OF NERVE. 269 have already alluded to the suspicion or idea that the elastic tissue was an organised residuum of the primary or embryonic intercellular substance (§ 210). As regards the capillary vascular retes, this view, especially when the vessels of bone are considered, appears highly probable j * but in the absence of positive observations we can only speak of it as a probability, that the periphery of the nerves at large, like the capillary retes, arises or is de- veloped from the primary or embryonic intercellu- lar substance. Chemical Composition of Nervous Matter. § 27<5. According to the analysis of Berzelius 1000 parts of cerebral substance contain — Water 800-0 Albumen 70-0 Cerebral fat ^ } 52-3 Phosphorus 15-0 Extractive matter (osmazome?) 11-2 Phosphoric salts and sulphur 51-5 1000-0 The chemical analysis of nervous matter, like that of any other system which is made up of a variety of constituents, will have a much higher value in reference to general anatomy when each of these constituents is regarded separately ; when as concerns the brain, for instance, the cortical and the central grey substance, the white or medullary * See in the section on the Vessels what is said of the origin and evolution of the blood-vessels of bone. 270 TUBULAR TISSUES. substance, the soft organic nerve, and the harder animal nerve, are distinguished and severally sub- jected to analysis. In the cerebral substance oil-globules are very rarely seen, fat cells perhaps never ; the fatty ele- ment of the brain would seem, therefore, to be mostly in a state of combination. Even the nerves present no other fat to the eye than that contained in the cells which so constantly accompany not only the trunks and larger branches, but the finest fasci- culi and even the primary fibres themselves. The brain in all probability contains a variety of salts, particularly phosphatic salts ; whether it contains any free acid or not has not been determined.* VESSELS. § 276. The vessels form a very considerable portion of the mass of the animal body. They are membranous branched tubes in which different fluids circulate ; these fluids being either fully elaborated blood, or lymph and chyle which flow into the blood, for its maintenance in adequate quantity. Some- times the ducts of secreting glands are reckoned * Macerated in water at the temperature of the air, the brain rapidly becomes soft, forming a kind of emulsion, in which state it has a peculiar and disagreeable odour, but that is neither fetid nor ammoniacal. Subjected to the action of boiling water, the cerebrum and medulla oblongata undergo scarcely any change of form ; but when the operation of boiling is con- tinued uninterruptedly for ten hours, both the medullary and cineritious part of the cerebrum appear rather contracted, and they become harder and more friable, and feel greasy. — See Dr. Davy’s Researches, Phys. and Anat. vol. ii. pp. 380, 313, and 320. — G. G. VESSELS. 271 among: the number of the elements of the vascular system ; vessels have, therefore, been classed accord- ing to their contents into 1st, lymph- vessels (lymph- atics and lacteals) ; 2d, blood-vessels; and 3d, secreting vessels. The lymph-vessels, with their associated glands, form the system of lymphatic vessels ; the arteries, and veins, and central organ of the circulation, form the system of blood-vessels ; the secretion-vessels form the sys- tem of secreting vessels or the proper glandular system. Vessels serve 1st, for the absorption of fluids from without, or the reabsorption of those which already received into the body' had escaped into the interstices of the tissues — the chyle and lymph- vessels ; 2d, for the distribution of the blood to every part of the body, as a means of enabling it to accomplish its destined offices, and to main- tain itself with its appropriate qualities — blood- vessels ; 3d, for the separation and removal of various matters from the blood, either to preserve this fluid in its integrity, or to effect certain pur- poses in the periphery of the body — secreting and excreting vessels. The blood-vessels, which belong to the system that is universally distributed, form networks in the periphery ; the lymphatics in their course form con- volutions called lymph-glands ; the secreting and excreting vessels, generally speaking, present nothing of the kind. The blood and lymphatic vessels are lined in the interior with the same serous mem- brane, a simple, and in the embryo tessellated epithelium. The secreting and excreting vessels 272 TUBULAR TISSUES. are either inversions of the corium or mucous mem- brane, or of their epidermis or epithelium. Lymphatic or Absorbent Vessels. § 277* The structure and function of the lympha- tics are the same in every part of the body ; their contents, however, vary, and they are therefore di- vided into chyle or lacteal, and lymph vessels. § 278. Lacteal vessels. The commencement of a lacteal vessel, according to Krause,* is an extremely delicate vesicle, or cellule, formed of the finest cellular substance, and produced into a narrow transparent canal, which consists of the inner vascular membrane alone ; this speedily anastomoses with the nearest delicate lacteal vessel ; and, in this way, a very dense or fine-meshed rete is formed. From the networks larger lacteals proceed, which, however, are, for the most part, no more than from the 20th to the 5th of a Paris line in diameter {Jig. 113). I have myself observed the lacteal vessels in many parts of the small intestines of a dog, on the villi of which the chyle here and there presented the appearance of a white earthy precipitate ; and, under similar circum- stances, in several others of the domestic animals and in man. Most probably, however, the roots of the absorbents were only imperfectly filled, and their commencements not at all distended in these observa- tions. Perfectly fresh villi, from the human intes- tinal canal of man and the domestic mammalia, pre- sented, under favourable circumstances, the following appearances : — The nuclei of the pyriform cylinder- * Handb. d. Mensch. Anat. Bd. I. S. 28. LACTEALS. 273 epithelium which covers the villi, present themselves in the guise of hollow pediculated vesicles {fig. 240, d ; fig. 241, b) ; the cavities of these appear to com- municate with larger lymph-vessels {a), which not unfrequently hang together and inosculate in the manner of the meshes of a thick net. From such networks the finest lacteals proceed ; and these, still continuing to inosculate freely, form a more open net with elongated meshes {fig. 241 ), very much in the manner of the hlood-vessels as they are seen in the longitudinal section of a cylindrical bone {fig. 6l). It seems probable, that secreting vessels of every kind take their origin in nucleated vesicles, of the same description as those of the lacteals ; the pre- sence of the chyle in these vessels might, therefore, with apparent propriety, he viewed as the effect of a process of secretion. The chyle has been already described in § 42, 50. § 279- Afferent, or Peripheral Lacteal Vessels These are disposed between the two serous laminae of the mesentery, sometimes by the sides of the blood- vessels and nerves, but sometimes apart from these, and run straight from the intestine to the mesenteric glands. The lacteals can be demonstrated to con- sist of three coats ; 1st, the universally present serous or inner tunic ; 2d, a layer of spirally-disposed, fine, reddish-coloured fibres, of the nature of the con- tractile or of the muscular tissue ; 3d, an outer coat of cellular substance, the component fibres of which run spirally around the vessel, as well as in the line of its length, the tissue being mingled wjth the fibres which Remak characterised as organic fibres. The peripheral lacteal vessels anastomose, or x 274 TUBULAR TISSUES. unite, but rarely, and always at very acute angles ; their diameter varies greatly, neighbouring vessels measuring one-tenth, one-half, and three-quarters of a line in diameter. They have numerous valves, which give them a knotted appearance externally (Jig. 108, a, e,f). They are formed in the same way as the valves of the veins, generally of two semi- lunar folds of the inner coat of the vessel, placed opposite one another, and having contractile fibres in their interior (figs. 114, i, and 115, e). The valves of the lacteals have the same functions as those of the veins, viz. to prevent the reflux towards the intestines of the fluids contained in the vessels, whilst the accumulation of this fluid behind, and mo- tion and pressure of every kind, tend to force it on towards the mesenteric glands and the heart. § 280. If we regard as chyle all the matters newly taken up from the intestines, and capable, by assimi- lation, of being turned into blood, and as lymph, all the fluids that are re-absorbed after having escaped from the current of the sanguiferous circu- lation, it is still obvious that the terms chyle and lymph, chyle-vessels and lymph-vessels, or lacteals and absorbents, are merely relative terms ; for the chyle-vessels do not transport newly-elaborated mat- ters only, but the lymph of the stomach and intes- tinal canal also ; and the lymphatics, those of the lungs and skin in particular, sometimes carry new matters, as well as such as have already and for some time existed as constituents or the body. The glands which we observe in such numbers at the root of the mesentery, and which are, therefore, called mesenteric glands, are, like the conglobate LACTEALS. 27 5 or lymphatic glands in general, convoluted or plexi- form masses of lacteals, assuming the appearance of solid fleshy organs. The mesenteric glands are in- terposed between the peripheral and central orders of abdominal absorbent vessels. By means of the glands in question, the chyle, probably with a view to its assimilation, is brought under the peculiar influ- ence of the organic nerves, at the same time that it is in intimate contact wTith a large amount of living, organic surface. The branches and subordinate divisions of the lacteals anastomose freely in these glands, and the finer twigs finally form a pretty uni- form, close, and fine-meshed rete, which again, gathering itself into minuter and then into larger branches, these unite and produce efferent vessels, which carry the fluid onwards in its course. The mesenteric glands are well supplied both with blood-vessels and nerves, which pierce them at every point, and surround the various subdivisions of the lymphatics. The various constituents of the mesen- teric glands, as now enumerated, are connected by means of cellular substance. The mesenteric glands, therefore, unite a portion of the periphery of the vascular and of the nervous system with their own proper substance, — with the reticular mass of lacteal vessels of which they prin- cipally consist ; and as the efferent vessels proceed, after the formation of the glands, in the same onward direction as the afferent vessels, they may be held as standing in the same relation to the blood-glands generally, as the fusiform nervous papilla {fig. 100) stands to the more ordinary form {fig. 99) ; and as the primary bundles of the nervous ganglia open up, 276 TUBULAR TISSUES. and resolve themselves into their primary fibres, which, after surrounding the ganglionic cells, again unite, and form an onward trunk {fig. 107), so the lymphatic glands, which have an analogous struc- ture, are often, and not inappropriately, spoken of as lymphatic ganglia ; and, by an extension of the same views, the spleen, thymus, thyroid, and supra- renal bodies, are sometimes mentioned under the name of blood-ganglia. Three forms of chyle-glands are distinguished : — 1st. False glands. These are small and loose, and form flattened, circumscribed net-works of lac- teals {fig. 108, c?). Several of the finer peripheral absorbents unite and compose a narrow-meshed rete, from which several smaller or a few larger inter- glandular vessels proceed, which generally then form a proper gland ; or they proceed at once, passing the proper glands, to empty their contents into larger vessels {fig. 108, c), or they become trunks them- selves, and advance towards the heart. Such false glands as have now been mentioned are generally found buried among loose cellular substance, in the vicinity of the periphery of the system to which they 2d. Scattered peripheral true glands. These are small, flat, lenticular, scattered, of a reddish grey colour, and from a quarter of a line to a line and a half thick, by from one to four lines in diameter. They are situated nearer to the periphery of the absorbent system than the central glands, generally betwixt these and the reticular or false glands, near the intestine, and between the folds of the mesentery. 3d. Accumulated , or central true glands. These INTERGLANDULAR LACTEALS. 277 are the largest chyle -glands met with ; they are generally lenticular and flattened, seldom perfectly circular, generally ellipsoidal or cordiform ; they lie at the root of the mesentery, near the receptaculum chyli or thoracic duct, and crowded together. They receive the whole of the chyliferous vessels which had gone to the false and to the isolated glands. The vessels which proceed from these glands are the cen- tral lacteal, or absorbent vessels, and either terminate in the thoracic duct or immediately in a vein ; they rarely form interglandular vessels, or vessels which as efferents, again form glands. On the anterior mesenteric artery of the dog, there is a singular long-shaped chyle-gland — the pancreas Asellii. Interglandular Lacteals. § 281. The afferent vessels often form ganglions or glands once and again, from which the proper central vessels then take their origin ; this is much more commonly the case with the lymphatics than with the lacteals. I entitle them interglandular vessels, from their connexion at either extremity with a gland, to the one of which they, of course, stand in the relation of peripheral, to the other of central vessel. They are generally larger than the periphe- ral lacteals, and contain fewer valves than these. § 282. From the central glands, lymph or chvle- vessels proceed, which terminate in neighbouring veins ; these lymph-ducts comport themselves in their course in the same manner as the central and inter- glandular vessels. At the points of their termination in the veins, various forms of valvular apparatus are 278 TUBULAR TISSUES. observed, which effectually hinder the reflux of the chyle just poured into the vein, or the entrance of the blood into the absorbent. I have observed three forms of these valves : — 1st. Simple opercular valves, of the same nature as those that commonly guard the mouths of entrant veins (compare Jig. 112, c, with Jig. 114, e). These are generally observed where the lymph-ducts enter the veins at acute angles. 2d. Semilunar valves, in pairs, of the nature of those generally observed in the trunks of veins, and which consist of two opposed semilunar folds of the inner coat of the vessel. This form of valve is usually found where a lymph-duct joins a vein per- pendicularly or at right angles to its axis (vide figs. 110 and 111 ; c, d, the valve closed; f, g, h, the valve open). 3d. Compound valves, made up of a combination of forms 1 and 2 {fig. 112). At the end of the valve e, the inner membrane forms two semilunar valves d, d * Central Chyliferous Vessels. § 283. Those vessels which bring the chyle from the glands directly into the thoracic duct are gene- rally spoken of as the central or proper efferent ves- sels. They generally quit the glands few in number, and are of larger size and shorter than afferent * In the horse it is not uncommon to meet with these lymph- ducts, or absorbents, terminating directly in the veins. In other domestic animals, and in man, I have never seen any arrangement of the same kind that was not questionable. In all probability, however, they exist generally. CENTRAL LACTEALS. 279 vessels ; they are also, like the interglandular ves- sels, beset with fewer valves than the peripheral lacteals and absorbents. They collect, for the major part, in the root of the mesentery, around the supe- rior mesenteric artery, and over the abdominal aorta, where they form several trunks, about half or three- quarters of a line in diameter in man and the smaller domestic mammalia, from a line to a line and a half in the horse, ox, &c. ; and these, with such acces- sions as they receive from the central lymphatics, pass over, for the most part, and end in the recepta- cle or reservoir of the chyle, situated to the right of the abdominal aorta. § 284. The receptaculum chyli is the dilated, and often branched varicose commencement of the trunk or principal vessel of the absorbent system, in which the major part of the chyle, and of the lymph of the abdominal extremities, is collected and mineled. § 285. The thoracic duct, generally simple, but still accompanied by certain central vessels, conveys the mingled lymph and chyle on the right of the aorta, by the side of which it enters the thorax ; but, by and by, dipping under the great artery of the body, it crosses between that and the body of one of the dorsal vertebra to the left, and pours its contents into the left axillary vein in man and the mammalia. Mingled with the blood, the lymph immediately en- ters the right side of the heart, and, being sent from thence, it undergoes exposure in the lungs, and, in all probability, receives its ultimate developement as blood in the course of the lesser circulation. The matters taken up along with the chyle from the intestines, which are unavailable in the economy, 280 TUBULAR TISSUES. and the effete substances, which proceed from the workings of the machine itself, are abstracted by various systems of depurative organs: — superfluous water by the lungs, the kidneys, and the skin ; salts by the kidneys and skin ; carbon by the lungs and liver ; azotized matters by the kidney ; hydrogen by the liver ; volatile and odorous matters by the lungs, the skin, See., in the shape of watery vapour, carbonic acid, bile, urine, faeces, &c. Lymphatic Vessels, and Lymphatic Glands . § 286. These, in appearance, structure, &c., are identical with the lacteals and mesenteric glands. The lymphatics arise as retes in all the soft parts of the body (Jig. 108), particularly under all the ex- ternal and internal surfaces, surrounded by much finer vascular capillary reticulations. They, by and by, combine into particular vessels, and these take their course in the subcutaneous or submembranous, and interstitial or interorganic cellular substance, generally at no great distance from the subcutaneous veins ; they then approach the principal vascular and nervous trunks, forming false lymphatic glands, or fine-meshed, circumscribed networks in their course (fig. 108, d), and also peripheral (A, A) and central glands or ganglions, in the spaces filled up with loose cellular substance. The central lymphatic glands appear to form finer transition networks than the lacteal glands. The lymphatic glands generally present themselves in clusters, and much more regularly in certain situa- tions than in others, viz. where the great vascular and nervous trunks divide to supply internal organs LYMPHATICS. 281 or the extremities, and where these subdivide to fur- nish particular sections of the limbs : — about the root of the lungs, the bottom of the neck and angle of the jaw, the axilla and bend of the arm, the groin and ham, &c. They are always embedded among loose cellular substance, are of a reddish yellow or reddish grey colour, of different sizes, flattened and of a len- ticular shape, or more elongated. The lymphatic glands that surround the first division of the bron- chi are of a slate grey, or black colour, which is generally deeper the older the subject is. The most remarkable clusters of glands are — 1st. That about the angle of the jaw and top of the larynx, the laryngeal cluster. 2d. The cesophogeal cluster, which lies deeper and lower down than the preceding. 3d. The cervical cluster, at the bottom of the neck. 4th. The axillary cluster, lying upon the axillary artery, vein, and nervous plexus. 5th. The inguinal cluster, lying upon the femo- ral artery, vein, and crural nerves. In the thorax : — 6th. The cardiac cluster, lying upon the great issuing and entering vascular trunks and cardiac plexus of nerves. 7th. The bronchial cluster, lying upon the first division of the bronchi, and the arteries, veins, and nerves of the lungs. In the abdomen : — 8th. The hepatic cluster, lying over the hepatic vessels and nervous plexus. 9th. The splenic cluster , between the laminae of 282 TUBULAR TISSUES. the gastro- splenic ligament, and over the splenic vessels and nerves. 10th. The lumbar and pelvic clusters, over the division of the abdominal aorta, and over the pelvic arteries, veins, and abundant nervous plexuses. Lymphatic inter glandular Vessels. § 287. Between the upper and lower part of the neck, and between the first and second articulations of the extremities, we observe large lymphatic ves- sels, which I propose to designate by the above title, inasmuch as they are afferent vessels to peripheral and efferent vessels to central glands, and connect these with each other ; by such vessels are the glands at the bend of the arm connected with those in the axilla, those of the popliteal cavity with those of the groin, those of the superior part with those of the lower part of the neck. The vessels in the latter situation are very large in the horse, often of the diameter of a good-sized goose-quill, and lie by the side of the trachea and behind the carotid artery (fig. 109). Efferent Lymphatic Vessels and Lymph Ducts. § 288. The efferent or central lymphatic vessels (fig. 108, bf) connect the central glands with the thoracic duct ; the lymph-ducts pour the central lymph immediately into the veins. The valves which guard the anastomoses thus formed are of the same description as those that protect the in- osculations of the chyliferous ducts with the veins (figs. 110, 111, 112). LYMPHATICS. 283 § 289. As the very finest lymphatics are still considerably larger than the system of intermediate peripheral blood-vessels in the passage of arteries into veins, wounds, abscesses, &c. may give occasion to the entrance into the general circulation of pus and other corpuscles of larger sizes than the blood- discs. These flow readily enough on to the heart ; but forced into the lungs, they are apt to stick fast in the capillaries of these delicate organs, impeding the circulation through them, and after the lapse of a few hours giving rise to exudations and to the formation of cytoblast tubercles (§ 108 and 109).# § 290. Indubitably, also, stases of the lymph and chyle occur in the glands connected with the lacteal and lymphatic vessels, either in consequence of the coagulation of their contents, or of inflamma- tion of the vessels themselves. The effects of such stoppages are not only frequently obvious among the larger glands in depositions of albuminous matter, the solvent of which, the serum, has been removed by absorption, but also in the innumerable peri- pheral false glands. In the scrofulous diathesis, it is well known to what an extent the central as well as the peripheral lymphatic glands will enlarge ; and when examined microscopically, their pathological * In examining the bodies of an unborn foetal horse, and of one that had just been born, I found the glands about the upper part of the throat in a state of suppuration, the interglandular vessels filled with pus, and in the lungs the usual consequence of this, viz. rounded cytoblast tubercles with pulpy contents. In two other instances I had no difficulty in discovering numer- ous pus-corpuscles mingled with the blood. In these instances there was suppuration of an extreme part, and cytoblast tuber- cular formations in the lungs. 284 TUBULAR TISSUES. contents, besides imperfect exudation -corpuscles, present albuminous granules and amorphous coagula in quantities by so much the larger, as the glands examined belong more completely to the periphery, and as the formation of fibrine seems to have been rendered difficult by the discrasy of the fluids or general cachectic condition of the individual. § 291. With regard to the origin and develope- ment of the lymphatics little is known. In the im- mediately succeeding section upon the blood-vessels, the views most reconcilable with our knowledge of other analogous points will be found detailed. THE SANGUIFEROUS SYSTEM. § 292. The sanguiferous vascular system com- prises the heart and the entire series of branched membranous tubes which, taking their rise from the heart, are distributed to all parts of the body, and from these return again to the central organ whence they set out, receiving the lymphatic vessels when near the end of their backward course. The blood-vessels are of two kinds, which differ from each other both with reference to structure, and to the part of the circulation in which they are severally engaged. Vessels of one kind are remark- able for the strength, thickness, and high elasticity of their walls, and transmit the blood from the heart to every part of the body, — these are the arteries ; vessels of another kind are distinguished by the thinness but toughness of their parietes, and return the blood from the extreme parts of the body to the heart, — these are the veins. The cir- culating system itself naturally falls into two great THE SANGUIFEROUS SYSTEM. 285 divisions : tlie one having reference to the system at large — the systemic, aortal or greater circulation ; the other to the lungs — the pulmonic or lesser cir- culation. The first consists of the left auricle and ventricle of the heart, of the aorta and its branches, and of the veins which the aortal system supplies ; the second comprises the right auricle and ventricle of the heart, the pulmonary artery and its branches, and the pulmonary veins. Sometimes the peculiar circulation of the liver is spoken of apart, and under the title of the portal circulation, as a third form of circulation ; and it certainly is unlike aught that we observe in any other part of the body ; the whole venous blood of the chylopoetic system, instead of being poured into the great returning trunk of the system in its vicinity, to reach the heart immediately, being first collected into a single vessel, and this undergoing division in the substance of the liver, like an artery, before the round is completed.* § 293. The end of the greater circulation is to supply all parts of the body with decarbonized blood, which is essential to their nutrition and to the manifestation of their appropriate vital endow- ments. The object of the lesser circulation is obvious : it is to expose the blood which has re- turned to the right side of the heart of a deep black colour, loaded with carbonic acid and impurities we may presume, and become unfit in this condition for the uses of the economy, to the action of the atmospheric air which is taken into the lungs ; by * The valuable observations of Mr. Kiernan should be con- sulted concerning the blood-vessels of the liver. — See Philos. Trans. 1833, part 2 . — G. G. 286 TUBULAR TISSUES. which it is freed from much carbon and watery vapour, and during which it acquires a bright ver- milion colour, and is again fitted to minister to the wants of the economy. The circulation through the portal vein effects the purification of the blood mixed with chyle from carbon and hydrogen, and perhaps from certain foreign matters which have been taken up from the intestines ; it also serves for the secretion of the bile. There is, therefore, an obvious similarity between the objects of the cir- culation through the lungs and of that through the liver ; carbon and hydrogen, or water, are the grand elements separated by each, these substances passing off from the lungs in the gaseous and vapor- ous form, from the liver in the shape of a peculiar fluid, which immediately becomes, to the best of our knowledge, an important agent in chymifica- tion and chylification.* The trunks and branches of the arteries and veins generally lie side by side *' Dr. Willis has lately given an ingenious and interesting account of the “ Signification and Ends of the Portal Circula- tion,” ( Loud. and Edinb. Monthly Journal of Medical Science , September 1841), in which he brings many facts and arguments to prove it a means of economising arterial blood. Had the liver been supplied direct from the aorta, it must have had a vessel of a calibre equal to the sum of the whole of the vessels whose refluent blood is collected into the trunk of the vena portae. This would have implied the necessity for larger respiratory and central circulating systems than under existing arrangements are found sufficient ; for the bright blood of the abdominal viscera, after having vitalised the organs to which it is distributed, though effete in one sense, will still afford the elements of bile if sub- jected to the peculiar elective affinity of the liver. There is nothing, he thinks, in the blood of the portal system which fits it more than any other blood to afford bile. In the two lowest THE HEART ARTERIES. 287 in their course, and are very constantly accompanied by nerves of greater or less magnitude according to circumstances. The Heart. § 294. The heart is a powerful muscle having four cavities or chambers in its interior, the entrances to, and exits from which, like those of a double- action pump, are guarded with valves so disposed that by the simple alternate contraction of the auricles and ventricles, the blood which is pouring in upon it from the vente cavse and pulmonary veins is necessarily forced into the great arterial trunks which here take their rise (§ 53 and § 246). The Arteries. § 295. The arteries receive the blood imme- diately from the ventricles of the heart, and dis- tribute it to all parts of the body. They are divided into the arteries of the greater circulation, or aortal system, and those of the lesser, or pulmonic circu- lation. The walls of the aortal system of arteries are thicker and stronger than those of the pulmonic system, in the same proportion as the walls of the left ventricle are thicker and stronger than those of the right, and as the resistance to be overcome in sending blood to the extreme parts of the body is greater than that which is met with in supplying classes of vertebrate animals, where the lungs become cellular sacs (amphibia), or are replaced by gills (fishes), and where we may presume it a matter of still greater moment to economise the arterial blood that is formed, there is an extension of the same system of circulation to the kidneys, which, in the two higher classes of the vertebrata, is limited to the liver. — G. G. 288 TUBULAR TISSUES. organs placed so near the centre as the lungs. The aorta and pulmonary artery mostly divide at acute angles into branches of progressively greater degrees of minuteness, and finally into terminal capillary networks and festoons, or vessels intermediate to the arteries and veins properly so called. Both aorta and pulmonary artery consist of three layers or coats : 1st, an internal serous coat (§ 126 and § 128) covered with a simple epithelium, which frequently passes over into a cellulo-fibrous variety of epithe- lium, which in the capillaries seems often to con- stitute the sole boundary of the canal ; 2d, a middle, and in reference to the diameter of the artery, a thick tunic of elastic substance {fig- 55), wdiich surrounds the vessel in several layers, and is the principal element which gives to the artery its strength and distinguishing elasticity ; 3d, a cellular external tunic which surrounds the vessel and con- nects it with the parts in the vicinity {fig- 50). The pulse is produced by the sudden increase in the quantity of blood contained in the arteries which is effected by each contraction of the left ventricle and the consequent expansion of the blood it contained. The wave of blood once pushed into the arteries, the stream is kept up by the elastic force of the vessels themselves, which suffices to carry it to the entire periphery of the body. The elasticity of the arterial parietes acts precisely in the same way as the air-cistern in such an hydraulic machine as the fire-engine, in which, though the stroke is only given at intervals, the stream is still sent forth without interruption, though it may be with jerks or increased impetus at the moments of renewed force; ARTERIES. 289 in the ultimate divisions of the arterial system the blood flows in one continuous and even current. The stroke of the heart itself against the walls of the chest depends on the push forward of the entire mass of the organ raised upon the great arterial trunks which its action has just filled to the utmost, and given a tendency to assume a straight line instead of the curved one which they present when partially filled or empty. The arteries generally run deeper in their course than the veins, and when divided do not collapse like these vessels ; on the contrary, they continue rounded as before. The arteries taken all together may have a capacity about half as great as that of the veins. § 296. The pulmonary artery conveys venous blood ; it divides into branches along with the bronchi, and forms delicate capillary reticulations around the pulmonary vesicles {fig. 145, very highly magnified, figs. 213 and 159). At its origin or commencement in the right ventricle, the inner membrane of the artery forms the semilunar valves {fig. 121), wdiich are fashioned very much in the same manner as the valves of the trunks of the veins {figs. 114 and and g, g ), save that they are three, not two in number, and, by reason of the quantity of elastic tissue they inclose, con- siderably thicker and firmer. The root of the aorta is guarded precisely in the same way. The semilunar valves prevent the regurgitation of the blood, just thrown from the ventricles of the heart, back upon the cavities during the interval of their diastole, when they are in a state of relaxation and themselves getting filled with a fresh supply of u 290 TUBULAR TISSUES. blood from the fountain of the venous sinuses and auricles. § 297* With any interruption of the breathing, the circulation of the blood in the periphery of the lungs suffers a pause ; and the interruption con- tinuing, the stasis extends to the pulmonary artery ; the right ventricle, the right auricle, the venae cavae, and the veins generally of the greater circu- lation, then become congested with blood, and so remain till life has fled. In those, therefore, who have died from suffocation — drowning, hanging, & c., the whole mass of blood is venous, and is contained in the arteries of the lesser, and in the veins of the greater, circulation. § 298. Should any bodies larger than the blood- discs enter the veins or the lymphatics, they are sure to be arrested in the capillaries of the lungs, when they give rise to exudations of the plasma or liquor sanguinis through the parietes of the vessels into the pulmonic tissue and the formation of tubercles.* § 299- The aorta arises from the left, as the pulmonary artery takes its origin from the right, ventricle of the heart ; its semilunar valves are stronger than those of the pulmonary artery, and the Arantian bodies in the middle of their free edges are larger and more distinct. The aorta shortly after its origin begins to form an arch towards the vertebral column — the arch of the aorta — from which in man three vessels, in the hog and the carnivora two vessels, and in the gramini- Vide what is said in § 289 and the accompanying note. ARTERIES. 291 vorous domestic mammals a single vessel, arise to supply the head, neck, and thoracic extremities. The aorta from the arch onwards has different names in different parts of its course, — the thoracic aorta, and the abdominal aorta — and supplies the trunk, the thoracic and abdominal viscera, and the inferior or abdominal extremities with blood. Where branches come off from the main trunk, it is com- mon to observe an infundibuliform enlargement to facilitate the entrance of the blood. This arrange- ment is particularly conspicuous at the origins of the intercostal arteries. It rarely happens that anastomoses or communi- cations take place between arteries of considerable size ; we have exceptions to the general rule, how- ever, in the communications of the cerebral with the vertebral arteries, and of the cerebral arteries with one another in front of the pituitary body to form the circle of Willis. We have also the vascular arches of the mesentery formed by the communi- cations of the large branches of the mesenteric arteries. The arteries advance tortuously in parts that are subject to enlarge upon occasion, as in the uterus ; sometimes the tortuous course appears to he instituted for the purpose of retarding the blood, in the testes for example. When the arteries have reached the organs for which they are destined, they subdivide into branches and minuter twigs, which generally in- osculate freely. The vessels that proceed from the last of these inosculations form the peripheral or capillary networks which themselves end in the veins. 292 TUBULAR TISSUES. § 300. The peripheral portion of the sanguifer- ous system presents itself under a variety of appear- ances, as a glance at the figures from 122 to 135, and from 137 to 152, will render obvious. In general, it bears a close resemblance to the peri- pheral expansion of the nerves of the corresponding part of the body, inasmuch as the terminal plexuses of the nerves form a more or less continuous and closed rete, the meshes of which inclose similar meshes of the capillary arteries.* * * § The terminal loops of the nerves are also accompanied by very similar terminal loops of the arteries or intermediate capillary vessels.! Even the particular forms of peripheral nervous distribution have their analogues in the peripheral vascular system.! The capillary vessels (fig. 6, A, b, b, b ; jig. 21, e, e, e) are the medium of transition from arteries to veins, and they form either simple nooses (fig. 6), or they run tortuously {fig. 21), or they form various meshes, or convoluted rete mirabiles {figs. 151 and 152). Such varieties of terminal distribution of arteries as are sketched in figs. 122-135 have been specified. § In the skin and mucous mem- * Compare the peripheral distribution of the nerves {fig. 93 at b, b,figs. 95 and 106) with the vascular networks (figs. 144, 145, 150, and 213). •j- Compare the terminal loopings of the nerves (figs. 97 and 98) with those of the arteries (figs. 124, 125, 126, 127, and 137, 138) ; further, the compound nervous papillae (fig. 93, d, d) with similar convoluted tufts of vessels (fig. 139). ! Compare the convoluted nervous papillae (figs. 99 and 100) with the erectile vessel (fig. 119) and the Malpighian body (fid- 152). § Vide explanation of these figures. ARTERIES. 293 branes these simple and compound festooned or looped vascular arrangements are always the more remarkable the more sensitive and active the parts are. The capillary nets are here and there so thick that when completely filled, the intermediate spaces almost disappear {Jigs. 146 and 148). The parietes of the larger vessels, such vessels, namely, as are still visible with the naked eye, have their own vessels and capillary nets as well as other organs (vasa vasorum), and are surrounded by nervous loops which for the most part belong to the organic system. The branches, too, are surrounded by fine networks of absorbents which seem to belong to them in especial. In many parts of their periphery the arteries compose what have been called wonderful nets — retia mirabilia — of different forms ; these are in- tricate, tangled reticulations of vessels.* Of the hall-shaped retes just referred to, there are many varieties, one of wdiich, of a more flattened form, from the thyroid body of a child, is represented in Jig. 146. J. Muller discovered a peculiar form of the arterial branches in the erectile organs, which he has characterised under the name of helicine — arterise helicinse. These are spirally wound varices, which now appear to end in blind sacs, and again to advance as branches of smaller diameter, or to pass over into venous branches {Jig. 155) ; it is * Vide Jig. 151, which is from a peripheral rete of the supra- renal capsule of a child, after Berres; and Jigs. 152 and 153, after Krause; and Jig. 154, in which Malpighian bodies from the cortical substance of the kidney are represented. 294 TUBULAR TISSUES. not likely that they end as blind sacs at any time. With the complete injection of these helicine arteries, the bulk of the erectile organs, as of the penis, increases somewhat ; but proper erection only ensues upon the filling of the erectile veins (§ 306). In textures, which consist of parallel fibres and fila- ments, the muscles for instance {figs. 141 and 142), the minuter subdivisions of the arteries also run, for the most part, parallel between the fasciculi. § 301. The capillary arteries are not seen every where to pass directly into veins ; they have been supposed sometimes to form independent loops, par- ticularly in the placenta, many of these departing from common pedicles or stems, and expanding into tufts or pencils {figs. 134 and 135). This kind of termination, however, is more than doubtful ; the structure indeed exists, but the loops very certainly revert and anastomose with other arterial loops, or, after making a turn or two, they end in veins. § 302. The portal vein, the trunk of which is formed by the vessels which return the blood from the various chylopoetic viscera, is obviously assimi- lated to the arteries in the mode of its distribution through the liver, its peripheral expansions ending in the hepatic veins. Veins. § 303. The veins return the blood from the periphery to the heart. They arise as capillaries of the finest description from the capillary vascular retes in every part of the body ; but even in their origins they are larger than the arteries at their terminations, so that wherever the arterial and VEINS. 295 venous retes form distinct strata, the one is readily distinguished from the other (fig. 144). The veins unite into finer and then into larger branches and trunks, which are always both of greater diameter and more numerous than the corresponding arteries.* This is evident when we see every artery of the extremities so constantly accompanied by two veins, each of larger calibre than itself, to say nothing of the large veins which we find running in many places altogether unaccompanied by arteries, — the subcutaneous veins of the arm for example. The unions between the branches of veins occur for the most part at larger angles than the divisions of the arteries. The veins are by no means so uniformly cylindrical as the arteries, they are often irregular and knotty, and this not merely because of the occurrence of their valves, but from their being actually of different diameters in different parts of their course. Some veins seem even to have what * In a given length the veins seem to contain about four times as much blood as the arteries ; supposing the blood to flow with equal rapidity in both veins and arteries, consequently, about four times as much would pass through the veins in a given interval as through the arteries : or otherwise, suppose equal quantities of blood to be transmitted through each order of vessels in the same period, the motion must be about four times more rapid in the arteries than in the veins. It is very commonly supposed that the sum of the capacity of the branches of an artery in a given portion of their length is larger than that of the trunk from which they are derived. An experiment which I made upon the mesenteric artery would lead me to say that there was no perceptible difference in this respect; a certain length of the branches held as nearly as possible the same quantity of injection as the same length of the stem. TUBULAR TISSUES. 296 may be called normal dilatations or varices, which, under the influence of pressure by neighbouring muscles, assist the circulation in the same way as the lymphatic hearts of reptiles ; this is remarkably the case in the facial vein of the horse. The veins, from the thinness of their coats, are transparent ; when empty they collapse ; during life and when full of blood, they are much more readily compressed than the arteries ; the pressure exercised upon them, indeed, by neighbouring muscles is a means of assisting and accelerating the circulation through them. In spite of their thinness, the veins nevertheless consist, like the arteries, of three coats ; hut the structure of the middle one of these is different. In the veins it is not composed of elastic tissue as in the arteries ; it is, on the contrary, made up of fibres of fine organic muscular or contractile tissue, which run in long spirals, and under appropriate stimuli, both contract the diameter of the vein and diminish its length. § 304. The valves of the veins are observed either in the course of their canals or guarding the inlets of such branches as join them. 1st. The valves of the stems are of the same essential nature as those that guard the commence- ments of the aorta and pulmonary arteries, and that occur in the interior of the lymphatics. They are formed of duplicatures, or loose folds of the internal tunic, between the component laminae of which con- tractile fibres are interposed. These valves are not observed in the great venous trunks, and do not exist at all in the veins of the lungs, in those of VEINS. 297 the liver and glandular organs generally, and in those of the brain ; neither are they met with in the minuter subdivisions of the venous system in any part. In the larger veins the valves are double, and in opposition to one another (Jigs. 114 and 11 they are rarely threefold; in smaller veins they are simple, so that the free edge of the valve flaps against the opposite wall of the vein when it closes. From the structure and mechanism of the valves it is obvious, that whilst the current of the blood is free and unopposed by them when it sets in one direction, it immediately brings them into play, and causes an entire obstruction of the vessel should it by any force or accident acquire a disposition to move in the opposite direction (Jigs. 114-117, and explanations). 2d. The valves that guard the inosculations of veins with one another are very regular in their occurrence. They are formed variously : sometimes the smaller vein extends for a certain way into the larger (fig. 114, d, e) ; sometimes the fold of the inner membrane which lies in the angle of junction enlarges so as to overlap the mouth of the entrant vessel in case of need. When the pressure in the stem becomes greater than that in the branch, the semielliptical fold (fig. 114, d and e ) is then pressed against the opposite outer wall of the branch (fig. 11 6, d and e), and the return of the blood is pre- vented. The same form of valve also occurs at the entrance of lymphatics into veins, and at the points of junction of lymphatics with one another. We observe the same contrivance used to defend the extremities of the ureters against the reflux of the 298 TUBULAR TISSUES. urine from the bladder, and the terminations of the salivary glands in the mouth, against the regurgita- tion of saliva or other fluids. ERECTILE VESSELS AND ERECTILE ORGANS. § 305. When speaking of the contractile tissue (§ 241), it was stated that the erection of the erectile organs was, at least in part, owing to a kind of spasm of this tissue. This view is made the more probable on account of the regular occurrence of the peculiar contractile tissue in all erectile organs. The motions of the iris depend, in all likelihood, on the agency of the same kind of tissue. The erectile organs consist in great part of a venous rete, with relatively very small interspaces, which are occupied and traversed in all directions by arteries, nerves, contractile fibres, and by elastic, fibrous, and cellular tissue. § 306. Erectile Vessels. — There are two peri- pheral forms of arteries known which seem to de- serve this name, — the tendril-like or lielicine arteries, and the arterial retia mirabilia (§ 300). The vessels, however, the distension of which principally effects the turgescence and erection of erectile organs, belong to the peripheral venous system. These vessels are without valves, and are, as might be presumed, particularly developed in the male ex- ternal organ, and in the female clitoris. They are also very distinct in the spleen. The labia minora in the female are erectile organs, but in an inferior degree ; so are the nipples in woman and female animals generally. The structure of ERECTILE VESSELS. 299 erectile organs, wherever they occur, is essentially the same. In the penis the erectile veins are dis- tinguished into external and internal ; the former compose the glans and corpus spongiosum urethrae in great part, and are in communication with the dorsal vein of the member {fig. 118). They are short, knotted vessels which anastomose very freely with each other, and when filled leave no spaces between them. The veins emerge, for the major part, from the glans upon the dorsal aspect of the penis, and unite into branches that constantly become larger and fewer in number, until they finally compose a single trunk, — the great dorsal vein. The internal erectile veins are inclosed hy the strong fibrous tunic of the corpora cavernosa penis, and form the greater portion of its body. They present themselves under twTo forms, which, however, are only distinguished from one another by this, that in the one the branches are somewiiat tortuous and interlaced and form a connected rete, yet of such a kind that the larger stems run parallel to one another, but connected by numerous trans- verse canals, in the long direction of the penis ; whilst in the other the vessels look like coils of small intestines chiefly disposed transversely through the body of the organ ; vessels of this description are very remarkable in the great enlargement which occurs towards the anterior third of the penis in the dog during the sexual act {fig. 119). In the clitoris the veins are of the same kind as in the penis. The mode of distribution and of peripheral termination of the splenic veins bears a considerable resemblance to what we observe in glandular organs. The veins 300 TUBULAR TISSUES. at their peripheries expand into pediculated vesicles, ^something in the same way as the final divisions of the bronchial tubes {Jig- 120); and these, precisely like the air-cells, are surrounded by a very delicate vascular rete. The veins of the spleen, like those of the penis, communicate very freely with one another. § 307. The reticulations formed by the large veins of the erectile organs are penetrated in all directions by the web of mingled tendinous and contractile tissue which is sent off from the general investing sheath, and by the arteries which at in- numerable points end abruptly in veins from ten to thirty times their own diameter ; frequently, how- ever, forming fine retes upon the veins, and, in the hinder portions of the penis especially, falling into the tendril-like or helicine form of artery. These helicine arteries are rarer in the clitoris, and are not so well developed as in the penis. . The spleen, like the male organ, is penetrated in all directions by a reticular fibrous tissue in con- nexion with its general outer investing tunic. The spleen is beyond all question an organ susceptible of various degrees of injection with blood, and, therefore, of distension ; but it is not an erectile organ in the same sense as the penis or clitoris ; this, however, happens rather from the manner of its attachment than from any difference of structure. Were the spleen implanted upon a bone, it would upon occasion, and with any impediment to the return of its blood, become erected instead of being simply distended. § 308. Erectile Organs — So long as the blood flows unimpeded out of the erectile organs, they con- ERECTILE ORGANS. 301 tinue flaccid ; but with any impediment to the back- ward current of the blood, the flow by the arteries continuing as before, they become distended and erect. The nerves, surrounded by a larger quantity of blood, now become more sensitive. The erection, indeed, seems to depend immediately upon the state of the nervous system, being accomplished by the agency of the tonic contraction or spasm of the muscles and contractile fibres in the tissue. This spasm, as regards the male organ and the clitoris, only yields with the completion of the sexual act, when these organs fall flaccid again. But in those who have died by hanging and by decapitation, a certain degree of erection has sometimes been ob- served to remain for hours, and even for days after death ; this, however, is no vital act, but follows from the stiffening of the entire system of voluntary motion, by which the blood is retained in the organs into which it had been forcibly injected. It would seem that neither the more rapid action of the arteriae helicinse, nor the repletion of the venous rete of the corpora cavernosa in con- sequence of this, nor the action of the ischio-caver- nosi muscles, nor yet the compression of the dorsal vein against the symphysis pubis, are competent to produce erection of the penis, although each and all of these acts contribute, and are indeed essential to the effect ; but that it is principally and more immediately dependent upon the agency of those reddish fibres and fasciculi, which I regard as con- tractile tissue, which enter into the structure of the organ. I have already had occasion, oftencr than once, to mention this tissue as presenting 302 FORMATION OF TUBERCLE. itself in the composition of the scrotum, where it is known under the name of the dartos , of the nipple, of the skin in general, and of the iris ; and which appears every where to stand in a peculiar and especial relationship to the nervous system. The elastic tissue that surrounds the erectile organs is the active means employed for emptying these, once the erethism, under which the injected condition was accomplished, has passed away. § 309- It was my intention, in this place, to have given my views on the nature of inflammation, its causes, ends, and consequences ; but this I find I cannot do without exceeding the proper limits of my work. There is one morbid phenomenon, how- ever, of frequent occurrence, both in the human and animal body, which presents itself with and without inflammatory symptoms, but in intimate connexion with the capillary vessels which I shall touch upon as briefly as possible before proceeding to speak of the origin of the blood-vessels. The morbid phenomenon to which I allude is the FORMATION OF TUBERCLE.* § 310. Various and very dissimilar causes may bring about coagulation of the concrescible fluids of the body, — the chyle, the lymph, the blood, and some of the products of glandular secretion. Among the number of these causes may be reckoned : loss of the solvent medium, particularly the water (§ 23); * Concerning the Structure of Tubercle, see Mr. Gulliver’s figures 252, 253, 254, 255, 270, and 271, and his observations in Appendix. FORMATION OF TUBERCLE. 303 greatly retarded motion or absolute stasis ; the admixture of chemical reagents absorbed along with the chyle, the lymph, &c., such as acids, salts, pus, mucus, ichor, &c., or that penetrate from neigh- bouring parts in virtue of the law of endosmose. To these must be added mechanical causes, injuries of all kinds, pressure, bruising, solution of con- tinuity ; and farther, the influence of unusual temperature, — exposure to excessive heat, severe cold, &c. § 311. Should the diameter of the particles of coagulum, however produced, be greater than that of the capillary vessels of the lymphatic, sanguiferous, and secretory system, they will become impacted in the capillary rete (§ 289 and 290) and stop this up ; or, otherwise, should the capillary vessels be injured in any way, should they become compressed by extravasation around them for example, then may the pure blood itself suffer obstruction. In this way a local stasis is produced in the blood- vessels betwixt the part implicated and that at which the circulation is carried on by collateral branches and anastomoses, in the lymphatics and lacteals betwixt the glands and the periphery con- nected with them. It is easy to see, therefore, why the lymphatic glands, the lungs, and the liver, are so commonly the seat of tubercular depositions. The coagula first reach the capillary vessels of one or other of these organs, and there get set fast as a matter of course. The fluid that has passed unimpeded through the pulmonic circu- lation, in particular, will not be apt to encounter any impediment in the course of the greater 304 FORMATION OF TUBERCLE. circulation, unless perchance it he in some injured part. § 312. The consequence of any accumulation of fluids in a particular part is an increase of pressure upon its vessels, in the same proportion as the transmission of the fluids is impeded ; and then the distended parietes of the vessels suffer the more liquid elements of the compressed fluids to transude and to accumulate in the surrounding tissues, in which, according to their nature, they either coagu- late or form precipitates, the serum which is set at liberty being then absorbed by neighbouring vessels. In this way the concrescible and more or less organisable elements of the general circulating fluids accumulate locally, whilst the watery parts in- crease relatively within the circulating system ; the consequence of which is, that the general nutrition of the body suffers, that the vital functions at large are depressed, and that the predominating serum overwhelms, as it were, the enfeebled organs of secretion, and finally, the serous cavities ; the in- terstitial and subcutaneous cellular substances then get filled, and general dropsy comes to be associated with the local disease. This state of things may go so far as finally to interfere with the performance of the whole of the offices most essential to life, if the individual is not cut off by the particular implication of such an important organ as the lung or the brain. § 313. Tubercles present great variety in respect of numbers, constitution, extension over several systems or limitation to one, &c. The exudation takes place either into the tissue of the part impli- ALBUMINOUS TUBERCLES. 305 cated, or its deposition causes compression of this and wasting through want of due nourishment. Tubercles are conveniently divided, according to their constitution, into albuminous tubercles, fibrin- ous tubercles, and tubercles of a mixed nature. § 314. I. Albuminous or Unorganised Tubercles can only be produced from exudations abounding in albumen, poor in fibrine. They consist almost entirely of granules from the yoVo-th to the Ty~th of a Paris line in diameter ; but with the granular matter, nucleoli, nuclei, or cells, are mingled in quantity bearing relation to the amount of fibrine which the exuded fluid contained. In man the lymphatic glands are the common seat of these albuminous tubercles, and often attain the size of a walnut and even of a hen’s egg. In our larger domestic animals they are sometimes seen as large as a child’s head. They are of a greyish white or of a pure white colour, firm, but seldom fibrous ; they are subject to softening and solution, when they form a mixed compound of granules, cyst- corpuscles, and serum, with a few cytoblasts, the product of the living tissues around the tubercular mass, this being in itself incapable of suppuration ; sometimes this external layer of purulent matter is so abundant that the tubercle lies loose like a seed within its husk. What may be called false albu- minous tubercles also arise occasionally within the substance of the secreting glands, in the granular degeneration of the kidneys, for example. In the earlier stages of this disease indeed, the albumen is deposited in the tortuous uriniferous canals of the cortical substance ; in the fully - formed disease, x 306 TUBERCLES. however, it is met with among and between the tissues also. The albuminous or granular tubercle is with great propriety often spoken of as the scro- fulous tubercle, the disease being especially developed among scrofulous individuals. § 315. II. Fibrinous Tubercle. — The plastic exudations from the blood-vessels into the different softer tissues, which take place in consequence of impediments to the flow of the blood through the capillaries, produce fibrinous and organisable tubercles in the event of reabsorption not imme- diately occurring, or true purulent abscesses when the oxygen of the atmosphere finds immediate or mediate access to the deposit. Tubercles of this description, according to the circumstances under which, and the time during which, the exudation has taken place, the vital condition of the indivi- dual and the constitution of the organic part af- fected, present important varieties, which include every conceivable difference between the substance of any recent plastic exudation and that of a complete internal cicatrix. Taking degree of or- ganisation as the basis of a division, we may distinguish — 1. The Hyaline Tubercle. — This form is found, with traces more or less distinct of mingled cyto- blast formations, in the bodies of those who have died during the period or very immediately after the occurrence of copious plastic exudations ; it is rarely seen, from the rapidity with which it passes into 2. The Cytoblast Tubercle, in which nucleoli and naked cytoblasts at first appear ; with the FIBRINOUS TUBERCLES. 307 completion of the process of formation of the cell- germs, however, the tubercular deposit appears to consist entirely of these last, and of an interposed hyaline substance. When this organisation has gone a stage farther, the deposit may be entitled 3. The Cell-tubercle, the cell-germs or cytoblasts having now undergone transformation into cells. 4. Cellulo-fibrous Tubercle. — When the exuda- tion is very abundant and proceeds with great ra- pidity, with condensation of the surrounding tis- sues, it is only organised where it is in contact with the living sides of the cavity which has been formed. The periphery of the deposit in these circumstances forms an organised sac, inclosing a central mass, in which the organising process does not go beyond the formation of cell-germs or cyto- blasts. From this the serum is either absorbed, and the cytoblast tubercle, become a dry mass, re- mains for an indefinite period in this state, or if absorption does not take place, it runs speedily into suppuration. The dry cytoblast - tubercle, however, is never secure against suppuration ; sooner or later, and as a consequence of a second- ary effusion of serum, it softens, and may then suppurate. When the exudation takes place slowly, so that the tissues are merely infiltrated without being displaced and compressed, or when the tubercles are small, so that their central point is not too far removed from the healthy tissue around, the cytoblasts or cell-germs proceed in their evo- lution and become cells, which arrange themselves into fibres, and so form an imperfect cicatricular substance, a cellulo-fibrous tissue, which increases 308 TUBERCLES. the density of the organ in which it, is deposited, but which may go on for many years unchanged, and causing little or no derangement of function. 5. Filamentous Tubercle, Cicatricular or Or- ganised Tubercle. — This structure is only pro- duced under favourable circumstances in connexion with very slow infiltration of tissues with plastic exudation, and the organisation of this into more or less complete filamentous formations. If an exudation of this nature has happened equally into the substance of a considerable portion of a soft organ, such as the lung, for example, we have then general condensation of the tissue, termed variously hepatisation or induration ; if it have been more local, we have circumscribed induration ; and if the indurations be small and have occurred in different places simultaneously or successively, we have or- ganised tubercles. All such parenchymatous cica- tricular formations interfere in a greater or less degree with the functions of the organ in which they occur ; hut if the exudation does not con- tinue, they commonly remain for long periods of time without undergoing change ; they seldom soften, and without repeated exudations around them they cannot be brought to suppurate. The substance of tubercles is sometimes inter- mingled with pigmentary granules, cells and cel- lular fibres, like melanotic formations in general, — these constitute melanotic tubercles. § 31 6. Granular, cytoblast, and cell-tubercles, more rarely fibro-cellular tubercles, may all soften and become diffluent. This change must not, how- ever, be confounded with suppuration ; for, instead ORIGIN OF BLOOD-VESSELS. 309 of forming proper abscesses, they become changed into cysts filled with diffluent inorganic contents ; or they give rise to internal ulcers with a kind of gangrenous implication of the surrounding tissues (§ 289 and 290). They only suppurate when the air of the atmosphere has access to them, either more immediately, as when they are laid open, or mediately and by penetration, as when they are deposited in the lungs and near the surface beneath the skin. Origin of the Blood-vessels. § 317* Although the ovum, both at its own formation and during the earliest stages of the process by which a new being is produced, advances without the assistance of vessels (§ 123), still this is only so long as the process of developement consists in the formation of cells and the arrange- ment of these into the rudiments of the principal systems. The rudiment of the sanguiferous sys- tem itself is produced as a necessary preliminary from the cellular mass of the intermediate or vascular lamina of the embryo (§ 123). Whenever the formative process has to get beyond the simple arrangement of cells, in which it has hitherto con- sisted, and these cells must undergo transformation into the parts of dissimilar tissues, blood-vessels and blood become necessary, precisely as we ob- serve to be the case in regard to secondary or- ganisations (§ 82, 88, 111). The heart arises first as a simple excavation in the cellular mass of the vascular lamina; the blood- corpuscles then appear, and at the same time the 310 TUBULAR TISSUES. sacculate parietes of the heart, and by degrees the vascular arches and the entire circulating system of the periphery or of the membranes. The sanguiferous system in the foetus consists at first of a single loop, as it were : in the young embryo of the fish, for example, a single canal without branches takes its departure from the heart along the vertebral column, turns round at its ex- tremity, and returns as a venous current to the heart. From this loop new ones proceed inwards and outwards, and around these the already ex- isting mass of cells becomes more highly organised, and others arise, betwixt which the formation of vascular loops continues to proceed with the same effects ; in this way the embryo grows and attains its developement, its vascular system at the same time increasing continually, each element supporting the other, for without pre-existing cells no blood- vessels are formed, and without blood-vessels no parent cells.* From the first loops the principal trunks are formed, from the next in order the se- condary trunks, from those still later the branches, and so on, every blood-vessel advancing in its evolution with that of the organ to which it belongs, or of the organism at large of which it forms a part ; — the principal trunks were themselves ori- ginally capillary vessels. The primary capillary retes are variously formed during the general developement, hut they seem to * Blood-vessels only arise between or among cells, never in parts of higher formation, for example in tissues ; if they arise secondarily in these, it is only after a preceding fresh formation of cells. FORMATION OF BLOOD-VESSELS. 311 increase in dimensions commensurately with the increase which takes place in the organs that in- clude them ; should the organ expand in all direc- tions pretty equally, the original vascular rete will he found expanded in the same manner, as for example in the hones of the skull {fig. 66) ; should the organ, on the contrary, increase, especially in one direction, the vascular rete will he found elong- ated in the same degree, as it is for instance in the middle portions of the long bones (fig- 6l). § 318. The vessels themselves, in all probability, arise out of the newly formed intercellular substance in the same way as the white tubular fibres of the nerves and the branched pigmentary cells. Of the mode of origin of these and of their relations to the capillary vascular system, Schwann * has particularly spoken. Certain special cells are produced, which are first arranged into cellular fibres, and then becoming fused together form hollow tubes. The mode of origin of the blood-vessels can be followed in the formation and developement of the vessels of hone in the course of the process of ossification. In examining the injected and dried cartilage of the ear of a new-born foal, I could not determine whether the capillary retes, which were visible in different places {fig. 213), belonged to the invest- ing membrane, or to the substance of the cartilage itself; probably they belonged to the perichon- drium ; such close networks are not commonly seen in permanent cartilages. Any thing like close capillary retes first make their appearance with the * Mikroscop. Untersuchungen. S. 182. 312 TUBULAR TISSUES. commencement of ossification in the ossific carti- lages.* Whilst the cartilage-corpuscles disappear in the bone-producing cartilages of the foetus, a blended fibrous tissue arises, and within this nuclei and bone-cells, isolated and connected into strings, which arrange themselves concentrically around the cavity of the nascent bone- vessel ( Jig . 65, b ). Whilst the cartilage-corpuscles are disappearing in the embryonic cartilage, and it is becoming a con- tinuous fibrous tissue, a vascular network makes its appearance within it, the first rudiments of the new formation being evolved in the primary intercellular substance, and consisting of connected delicate fibres. Upon these fibres bone-cells are deposited. The rudimentary vascular rete thus produced is isolated at first from other similar formations and uncon- nected with any actual blood-vessel ; but by degrees one gets into communication with another, and then with some vessel in its vicinity, blood begins to flow through the reticulation, and the structure is com- pleted. From the crown of the outermost vascular arches thus formed, branches or leaders are sent off, at first in straight lines, but which soon bend round in * I must here refer to my most recent observations on ossifi- cation (§ 179 and 184), which I imagine remove all doubts of the bone-corpuscles being the nuclei of my bone-cells (§ 184), at the same time that they shew either that the medullary canali- culi, as they are called, do not exist as such, or that other cavities to which such an appellation is inapplicable have often been taken for them. Kobelt of Heidelberg, at the meeting of German naturalists at Freiburg in 1838, shewed preparations that confirmed these views. I have also been able to fill the finest vessels of the bones by injections thrown into the nutrient artery in the human subject. SECRETING VESSELS. 313 one direction like hooks, until they encounter and join ; each new arch produced sends off new shoots, which again bend round and meet their neighbours as before, and so the process goes on, and with it the formation of the bone. These shoots, when they first appear, are rounded, blunt, and closed at the extremities. Around the delicate vessels thus formed, flat bone-cells are deposited incessantly, by which the bony interspaces become thicker and stronger, and the vascular canals, on the contrary, are reduced in diameter. The vessels are readily distinguished in the midst of the bony reticulation (, fig . 213) ; the delicate fibres and filaments that were first formed are seen projecting from the edges of fresh bone when broken. When cut trans- versely across, the tubuli display their concentric layers of bone-cells {Jig. 65, b). At this point of the ossific process some cartilages remain stationary, and even in some of the softer parts of proper bones it goes no further, — at the ends of the medullary cavities of the long bones, for example. In the compact bones, however, it proceeds, for the meshes or spaces between the bony fibres get filled up with rounded bone-cells {fig. 60, i). Secreting Vessels. § 319. The secreting vessels are in one case branched sacculate involutions of the mucous mem- branes which proceed from the mucous lamina, or of their epithelia ; in another they are similar invo- lutions of the corium or its epidermis. As their purpose, so is their mode of origin different from that of the general circulatory vascular system. 314 EVOLUTION OF THE MUCOUS CAVITIES. They terminate, as a general rule, at their periphery in blind pediculated vesicles into which the peculiar secretion distils or percolates from the blood that is circulating in neighbouring vessels, and from which this is conveyed to the place of its destination or of its excretion ; the principal trunks of secreting vessels are spoken of as ducts of the glandular parts with which they are connected. They form the most essential and distinguishing element of se- creting glands. Evolution of the Mucous Cavities from the Mucous Lamina in the Embryo. § 320. The mucous or inner layer of the ger- minal membrane separates, as is well known, first from the serous and then from the interposed vas- cular lamina. By and by, along with the embryo, it is gradually pinched off from the vitelliculus or yolk-sac, which thus becomes divided into two cavities connected with one another. The smaller of these cavities, in connexion with the abdominal aspect of the embryo, furnishes the rudiments of the future mucous system. At first it presents no more than a simple nutrient cavity, as in polyps ; hut out of this, one after another, by evolution and involution, separation and outward opening, the various mucous cavities and the secreting organs lined with mucous membranes are evolved. The mucous system at large may he viewed as a chemical apparatus superadded to the mechanical system of muscles, bones, ligaments and cartilages, and to the dynamic one of the nervous system, by means EVOLUTION OF THE MUCOUS CAVITIES. 315 of which the necessary interchange of matter and the material relations with the external world are accomplished. The elongated intestinal chink, which is at first widely open towards the yolk-sac, closes anteriorly and posteriorly into blind sacs, — the rudiments of the mouth and anus ; and with ad- vancing evolution, the middle portion is closed like- wise and forms the small intestine, which, however, still continues in communication with the yolk-sac by means of a narrow canal — the vitellicular or umbilico-vesicular duct. In the mammalia this is speedily closed and rendered useless, its place being, at a very early period, supplied by the umbilical cord or vascular bond of union betwixt the parent and the embryo, the medium by which nutrient juices are brought for its use, and by which effete matters are removed from its economy. The in- testinal communication with the mouth is first established, and then that with the anus. The in- testinal canal is at first of large capacity and only of the length of the vertebral column ; it becomes relatively narrower in diameter by degrees, and is constantly growing absolutely longer. The simple intestinal tube consists at first of connected cellular filaments, so that it appears evenly granular when viewed under a suitable magnifying power ; it is only by and by that the muscular can be distin- guished from the mucous tunic. In the head the intestinal tube enlarges to form the fauces, and under the diaphragm to become the stomach, which lies at first transversely from left to right in the shape of the letter S, and forms a right angle with the oesophagus above, and with the small 316 ORIGIN OF GLANDS. intestine below. In ruminating animals it is divided by two constrictions into three cavities, the middle one of these being the largest. The small intestine is finally completely separated from the yolk-sac or umbilical vesicle. During the time that the be- ginning of the great intestine lies in the umbilical sheath and yet unincluded within the cavity of the abdomen, the rudiments of the cajcum appear. Near the posterior extremity of the still closed intestinum rectum, the allantois or urinary pouch has been produced at an early period. Origin and Evolution of the Glands , ivhose Ducts are lined with Mucous Membranes. § 321. Besides these simple evolutions as means for the production of simple cavities, only one of which accomplishes its ends with the period of birth, and therefore disappears, — the allantois, — the ramified secondary cavities grow from the in- testine, looking at first like blind lateral divari- cations from this ; but the chief canal, still branching off in determinate directions until the skeletons of the compound mucous glands, and those of the urinary and genital systems, of the lungs, liver, pancreas, &c. are evolved. The mucous canals of these last, getting finer and finer as the ramifica- tion extends, increase with the peripheral ex- pansion of the sanguiferous vascular nets that play around them, the two elements growing together out of the mucous and vascular systems, but always amidst the gelatiniform, and at present scarcely recognisable cellulo-fibrous substance which had ORIGIN AND EVOLUTION OF GLANDS. 317 been prepared beforehand for their reception ; in this way the destined limits of the gland are finally attained. The lymphatics and nerves of the glands are evolved at the same time ; and finally, from the still interposed but hitherto indifferent cellulo- fibrous tissue, the connecting cellulo - filamentous tissue. In the same way do the cutaneous glands, particularly the mammary glands, also commence and proceed in their developement, their ducts or skeletons and most essential parts being formed by a succession of ramified involutions of the corium. § 322. This mode of developement of the com- pound secreting glands from the central parts to the periphery, is in nothing analogous to the mode of origin and extension of the blood-vessels in the more persistent, though still transition cellular formations ; for example, in the bone cartilages during the period of their ossification (§ 318). Nevertheless, even as we observe the central and peripheral portions of the vascular system arising independently in the cellular primordial mass of the area pellucida, so do we in some instances observe what may be held as central and peripheral portions of the same mucous system, arising and attaining a certain degree of completeness before they meet and become fused, — the secreting parts of the kidney and testis, for example, and the excret- ing parts, consisting of the ureters, vas deferens, vesiculse seminales, &c., meet when they are severally well advanced in their developement. This is ob- viously very like what we see occurring in the embryo in regard to the manner in which the great venous 318 ORIGIN, ETC. OF SKIN AND MUCOUS MEMBRANES. trunks of the heart advance to meet the large peripheral veins which have been evolved contem- poraneously but independently. § 323. The progressive evolution of the mucous vessels takes place by a constantly repeated process of branching, until the destined limits of the gland to which they belong are attained. The size of these branched vessels becomes progressively smaller and smaller to their blind extremities ; whilst new ones are forming the old increase, and towards the peripheries of glands the secreting vessels are more crowded and of smaller diameter than they are at the membrane or integument from whence they took their rise, where, indeed, we commonly find a single trunk the representative of the entire series of ramifications which are connected with it. The Skin and the Mucous Membranes . § 324. The skin or common integument invests the whole external surface of the body, and serves individuals as the immediate means of isolation from the rest of creation ; it also proves a defence against many mechanical and chemical influences ; as an organ of secretion, too, it is in relation with the external media, surrounded by which men and animals exist. The secretions of the skin are the sebaceous matter and the sweat (§ 140 and 144), the constituents of which are water and watery vapour, carbonic acid gas, certain volatile matters cognisable by the sense of smell and different salts. In so far as effete or pernicious substances are thrown off by the skin, it is also a depurative organ. • The ORIGIN, ETC. OF SKIN AND MUCOUS MEMBRANES. 319 skin farther absorbs gaseous,* vapoury, and liquid substances from without ; and then, in alliance with the lungs, it is the great means of maintaining the body at the proper temperature ; and associated with the lungs, the kidneys, and the intestines, in regulating the quantity of water contained in the system. The skin, finally, is the organ of common sensation through the whole of its extent ; lastly, its sensibility becoming exalted or modified in certain parts, particularly the points of the fingers, it is the seat of the sense of touch. The skin consists, 1st, of the epidermis or cu- ticle (§ 136), with its involuted glands and its evoluted hairs ; 2d, of the corium, which, besides numerous nerves of sensation, blood-vessels, and lymphatics, contains a contractile elastic and cel- lulo-fibrous tissue in its constitution ; it also con- tains the sebaceous glands within its substance, and transmits the ducts of the sweat-glands. The * Dr. Dalton thinks that air penetrates the solids and liquids of the human body during life (“ Bibliotheque Universelle de Geneve,” t. liv. p. 130) ; and Professor Burdach is of the same opinion (“ Traite de Physiologie,” traduit par Jourdan, t. viii. p. 34). But Dr. Davy has given the results of experiments, most of which shew that air susceptible of extraction by the air-pump is not contained in the healthy animal fluids and solids, nor in the pus of abscesses, except when air may have had access to the pus, as in a case of empyema complicated with pneurna- thorax (“ Researches, Physiological and Anatomical,” vol. ii. VI. and p. 464). If, as alleged by Dr. Dalton, the drawing in and swelling of the hand, when applied to an exhausted receiver, be caused by the tendency of air contained in the part to escape, how could the common operation of cupping succeed, seeing that the air would issue through the incisions and quickly fill the glass? — G. G. 320 ORIGIN, ETC. OF SKIN AND MUCOUS MEMBRANES. corium is connected with subjacent parts by means of a quantity of lax cellular membrane, in which a large quantity of fat is deposited in health and with food in adequate quantities. As it is in part an organ of animal life, the skin is obviously placed in a kind of antagonistic relationship to the purely organic mucous membranes. § 325. The mucous membranes comprise the same constituent elements as the skin ; these are only modified in quantity and in quality, the mu- cous membranes standing in a different relation to the organism and to external objects from the skin. The peripheral indusium of the mucous membranes or epithelium, kept constantly moist, is softer and less horny than the epidermis ; their glandular inversions — the mucous crypts and mucous glands (§ 166-168) — instead of unctuous matter secrete mucus ; there are no proper sweat-glands, although it must be allowed that in the submucous cellular tissue we do here and there observe involutions that differ from the ordinary mucous glands, and approach the sweat-glands in appearance. The papilliform eminences which are visible in many parts of the mucous membranes, particularly on the surface of the tongue, are covered by corresponding processes of the epithelium. The corium of the mucous membranes is thinner and looser than that of the skin ; it forms numerous villi in certain situations for the purpose of extending the surface. The submucous cellular substance contains no fat, and in general connects the membrane with muscular tissues. The mucous membranes are in relation with MUCOUS MEMBRANES. 321 matters or fluids secreted from the blood and destined, 1. (a) for the maintenance of the individual, such as mucus, saliva, gastric juice, bile, &c., or ( [b ) for the continuance of the kind, such as the seminal fluid, the menstrual flux, the ovum in its passage along the Fallopian tube and during its sojourn in the uterus ; 2, for the elimination of effete and noxious matters, such as the urine, bile, &c. The mucous membranes are further the organs by which substances adapted for assimi- lation — meat and drink — are prepared and made fit to be received into the proper interior of the bodies of animals ; and by which also that process, the most immediately essential to life in all the higher orders of beings — respiration — is carried on. The mucous or muco-membranous system is therefore one of vast importance ; it serves as the grand instrument of the bio-chemical interchange of elements that takes place between the body and the matters external to it, with which it is in necessary relation. The innumerable villi with which we see the mucous membrane of the intestinal canal beset, are but contrivances to extend the absorbing- surface of the organ without adding materially to its bulk ; and the involutions of the membrane which we observe in the numerous secreting glands are no other than means to the same end, — the extension of surface, — but with the opposite pur- pose of abstracting from the organism, particularly from its circulating fluid, certain matters that are either necessary for other processes, or that were prejudicial if longer retained. Y 322 ORIFICES OF EXCRETORY CANALS. Valves of Excretory Canals. § 326. The secreting glands are consequently lateral productions either of the skin or of a mucous membrane. They shed the fluids, which they pre- pare from the blood, either upon the external surface or into a muco-membranous reservoir, from which none of it can return into the gland, in consequence of the existence at the orifice of the excreting duct of variously fashioned muco-membranous folds which serve as valves. The forms of these valves may be reduced to two : — 1. Wart-shaped Glandular Valves — The wart- like or nipple-like enlargement here opposes any pressure back upon the gland with a power which is in the ratio of the surface it presents in compari- son with that of the orifice or slit by which the duct terminates. We observe this kind of valve at the terminations of the salivary ducts, of the ductus clioledochus communis, of the tubuli uriniferi on the points of the papillary bodies, of the milk- ducts, &c. 2. One-sided Movable Glandular Valves Valves of this kind are like those of the veins and lymphatics, and like that which guards the foramen Thebesii in the heart : we have examples of them at the termination of the ureters in the bladder, of the seminal canals in the urethra, &c. It is also very common to observe contractile fibres in larger quantity than usual, and disposed in the annular form around the orifices of the excret- ing ducts of glands, by which these openings are guarded to a certain extent in the same way as the DIVISION OF GLANDS. 323 anus is by the sphincter ani, and the neck of the bladder by its contractile bundle. Division of the Glands. § 327. Something has already been said re- specting the division of the glandular system, under the head of the epidermis (§ 169), and an attempt made to present the glands according to their na- tural affinities in the form of a table (p. 169). What follows immediately may be regarded as an explanation of the table referred to. The cuticular glands have already been de- scribed (§ 139-144 and 1 66-1 69). The placenta has not been included among the blood -glands because it would seem, that those vessels only which are destined to nourish this deciduous organ form a connected rete with one another. The umbilical artery and veins which virtually consti- tute the placenta, cannot always he shewn to have any direct communication writh one another ; they form terminal tufts made up apparently of blind capillary loops, a structure of the existence of which conviction may be obtained by successful injections of membraniform placentas, such as that of the mare. The thymus,* strictly speaking, does not belong to the blood-glands, for it scarcely receives more vessels than seem necessary to nourish it. The group of bodies characterised as “doubtful glands” are very different from each other, but are not yet * There is reason to believe that the office of the thymus is simply to elaborate an additional quantity of nutrient matter at a period when this is most required by the economy. See Appendix. — G. G. 324 PROPER SECRETING GLANDS. sufficiently known to have their places assigned to them in a natural system of organic parts. Proper Secreting Glands. § 328. In his classical work on the intimate structure and formation of glands,* Professor Mul- ler has described and figured these essential parts in the organism of animals with his usual com- pleteness and accuracy. The secreting glands are soft, rounded bodies, of a colour varying from a reddish-white to a dusky-brown, made up of a con- geries of secreting, blood, and lymphatic vessels, and of nerves and cellular substance, which, from the blood circulated through them, prepare and pour into their variously shaped reservoirs certain peculiar fluids, which are finally conveyed away and discharged upon the external or upon one of the internal surfaces of the body, by means of an appropriate duct. The secreting glands are situated now in, now under, the compound membranes, now in the in- terior of the body, connected with surrounding parts by means of vessels, nerves, and cellular tissue. The degree of their complexity and their external forms are very various ; they are all in- vested with a fibrous tunic, and those that lie in serous cavities have a serous tunic in addition. Their essential and generally branched cavities either end as blind sacs, or as pediculated vesicles, or as loops, in either and every case surrounded by * “ Glandularum secernentium Structura penitiori earumque prima Formatione in Homine atque Animalibus,” c. tab. xvii. fol. Lips. 1830. SIMPLE SECRETING GLANDS. 325 a network of much more minute blood-vessels, and a scantier accompaniment of terminal loopings ge- nerally of organic nerves. The excretory ducts are now simple openings of simple cavities, now canals of great length and extreme narrowness ; these consist of the attenuated elements of the compound mem- branes upon which they terminate, of which, in- deed, they are involutions ; they are for the most part lined by a tessellated epithelium, seldom by a cylinder -epithelium ; they are either simple or ramified, and in some instances run into ample reservoirs, — the gall-bladder, the urinary bladder, the vesiculie seminales, — in which the product of their activity is stored up until time and circum- stance permit or require its discharge. The secreting glands in a state of health are nearly insensible, in the ordinary sense of that word ; they are, however, extremely susceptible of certain appropriate organic stimuli ; the seat of this susceptibility appears to be the vessels in general, but especially the contractile secreting vessels (on the origin and relations of these to the tegumentary system, &c. vide § 318-323 and 325). The secreted fluids are watery, or they are unctuous, or of a mixed nature, and contain min- gled with them the detached epithelial cells of the secreting cavities. The secreting glands are simple or compound. § 329. Simple Secreting Glands. — These form small sac -like cavities, and are styled follicles; they are contained in the substance of the corium (fig. 239, a and b ), or of a mucous membrane. These simple cuticular glands have been included 826 SECRETING GLANDS. in our account of the epidermis. The lobulated {fig. 239, f) and multilocular sebaceous {fig. 160 and 161), the botryoidal sebaceo-sudoriparous # and the mucous glands {fig. 42, c, d, p, n ; fig. 43, e,fi i, k ; fig. 44, c, d, e ; fig. 45, c, d, e ), strictly considered, belong to the compound glands. When several follicles terminate in the same peripheral cavity, they form with these what are called crypts. § 330. The mucous follicles are flat, lenticular, more rarely elongated and convoluted, and their vascular walls in relation to the extent of the simple cavity they inclose are relatively thick ^ their simple openings are wide and short ; in diameter they range from one-third of a Paris line to three Paris lines, that of their openings being from one- tenth to one-third of the same standard. The ma- jority of them lie in the mucous membrane itself; the larger among them, and those that are con- voluted, however, project in part or entirely among the sub-mucous cellular tissue. In general they occur scattered ; but in many places they are thickly clustered together. The mucus secreted by different mucous mem- branes, and even by different parts of the same mucous membrane, is different, — watery and diffluent here, there thick and tenacious, viscid and slippery, of a greyish or greenish-white colour, and soluble in or miscible with water with great difficulty. Chemically considered, mucus consists of water in large proportion, proper mucous matter or mu- * If the sudoriparous glands be found to consist of a single convoluted canal, as Gurlt believes, they must of course be classed with the simple ones. SEBACEOUS FOLLICLES, ETC. 327 cine, with a little soda, alcoholic extract with lac- tates, watery extract with phosphatic salts, and chloride of potash and soda. The microscopic ele- ments of mucus are epithelial cells and mucus- corpuscles, bodies made up of agglomerated granules (§ 35). § 331. The sebaceous follicles of the skin are, for the most part, present in smaller numbers than the mucous follicles of the mucous membranes. They generally open laterally into the hair-sheaths ; they always occur isolated, and are not so universal as the more compound sebaceous glands (§ 139) ; but they are commoner than crypts. The sebaceous matter is a sluggishly fluent oil, of the consistence of butter, in parts that are not provided with hair, and is either colourless or coloured according to the colour of the part of the skin which it anoints ; its colour being in the ratio of the pigmentary granules which it contains. According to Esenbek, 100 parts consist of: — Fat 24-2 Osmazome, with traces of oil 12-6 Watery extractive 11-6 Albumen and caseine 24-2 Carbonate of lime 2-1 Phosphate of lime 20-0 Carbonate of magnesia 1-6 Acetate and muriate of soda, and loss 3-7 100-0 § 332. The sebaceous crypts are of different sizes in different parts of the body, and consist of larger or smaller, superficial or deeper blind sacs, included in the skin or mucous membranes, the 328 SECRETING GLANDS. parietes of which are beset with follicles, which pour the mucus or sebaceous matter into the cavity (§ 142). § 333. Compound Glands When glandular cavities are composed of many smaller ones, simple or ramified, they are spoken of as compound glands. Glands of this order are distinguished into 1, ag- gregated glands ; 2, acinose or vesicular glands ; and 3, tubular glands. 1. The aggregated or associated glands are mere groups of simple glands or pediculated fol- licles of various form, which end in a common excretory duct. To this order of glands belong the compound sebaceous glands (§ 139-141, jig. 42, c, d, o, p; jig. 43, c, e, f; jigs. 44 and 45, l60 and 161). The Meibomian glands {jig. 158), which belong to the sebaceous glands, form links of transition to the compound vesicular glands of the second order ; to this place also are to be referred the larger and more complex mucous glands, — the prostate and Cowper’s glands. 2. The vesicular compound glands consist, at the limits of their subdivisions, of variously shaped membranous vesicles, — acini, — from the -gLth to the To-th of a Paris line in diameter, which, upon the periphery of the glands so constituted, and they are generally of considerable size, appear mutually to compress each other, and to become polyhedral in their outline ; the pedicles of these vesicles unite, as they do in the aggregated glands, into tufts ; or the pedicles are longer, and combining they form secreting vessels which represent the twigs ; these, again, unite and form the branches ; and these last LACHRYMAL GLANDS. 329 coming together constitute the trunk of the glandu- lar tree. This trunk is generally simple, and forms the excretory duct of the entire gland. The secreted fluid is poured out more or less remotely from the gland that prepares it, either gradually and incessantly, or in larger quantity at particular times. The first generally botryoidal combinations of the elementary vesicles form the glandular granules or acini which are distinguishable by the naked eye ; a certain number of these clustered together form the lobules, and these in their turn, connected by cellular substance, constitute the larger lobes, when the structure of the glands happens to be lobular. To glands of this description belong the lachrymal glands, the salivary glands {figs. 136 and 137), and pancreas, the lungs, the liver, and the milk or mammary glands. The fluid secreted by the lachrymal glands is watery and colourless ; it consists of from 96 to 99 per cent of water, and of from 1 to 4 per cent of solid matter, made up of a peculiar yellowish extrac- tiform substance, common salt, and traces of soda, phosphate of lime, and phosphate of soda. Accord- ing to Fourcroy and Yauquelin, human tears con- tain hut one per cent of solid matter, a compound of the yellow7 extractiform matter not entirely soluble in wrater, and of common salt. The tears of the domestic mammalia are in all probability little dif- ferent from those of man. The microscopic elements of tears are a few7 tessellated epithelial cells from the surfaces of the excretory ducts, and some granules ; if the fluid of the lachrymal sac he examined, there will be found mingled with it the campanulate cvlin- 330 SALIVARY GLANDS. der epithelial cells of the conjunctiva ; the products of all the glands that stand in relation to the mucous membranes are always mixed with the detached cells of the glandular epithelia as well as of those with which the ducts are in immediate relation at their orifices. The saliva, examined as it distils from the mouth, contains the large squamiform, granular epithelial cells of the mucous membrane of the mouth, and mucus-granules. Pure saliva is nearly as transparent as water, sometimes watery, some- times slightly viscid ; during the assumption of food it is said to be alkaline, at other times it shews acid reaction. According to the analysis of Mit- scherlich and Gmelin it consists of water with about 1|- per cent of solid matters. 1000 parts were found to contain — Water 985-00 Chloride of potash 1-80 Lactate of potash 1-63 Lactate of soda 0-87 Soda with some mucus 1-64 Phosphate of lime 0-17 Silica 0-15 Sulphate of potash Sulpho-cyanate of potash ? Mucus, about 1-40 Salivary matter, — salivin, ptyalin ... 4-50 Watery extractive 1-50 Alcoholic extractive 1-30 999-96 The saliva of the horse is transparent, colour- less, slightly viscid or susceptible of being drawn into threads, without smell and without taste, which SALIVA. 331 last qualities depend, doubtless, on its saline con- stituents according essentially with those of the human saliva ; it shews alkaline reaction, and, like that of man, deposits flocks when allowed to stand at rest. A drachm of this saliva requires, accord- ing to Schulz, a grain of vinegar to saturate it ; a drachm of this neutral saliva set aside in a cool place for twenty-four hours required two drops of vinegar to neutralise it again ; and the same thing was found to happen again and again until putre- faction commenced. After an interval of a week it was found very acid. The reappearing alkalescence depends, according to Schulz, upon the develope- ment of ammonia ; urine is found to comport itself in the same way. According to Lassaigne, the saliva of the horse contains essentially the same principles as that of man, as these are given in the analysis of Gmelin and Mitscherlich. In the saliva of the parotids Gurlt found but 0'J87, in that of the sub- maxillaries, on the contrary, 3*617 per cent of solid matter. As the water of the watery secretions in general increases with the quantity of water taken into and contained in the body, and particularly during damp and cold weather, such discrepancies in the relative amounts of watery and solid con- stituents ought not to surprise us. In fact, not only do the inorganic salts of the saliva, but its animal constituents — the osmazome and ptyalin — differ according to circumstances, both in the same and in different individuals. The saliva of the carnivora, and particularly of the dog, has been found more dense, more viscid, and to contain 2*58 per cent of solid matter. 332 BILE. The fluid of the pancreas, as the researches of Leuret and Lassaigne, and of Watrin teach us, is scarcely different from that of the salivary glands of the mouth. The Bile is the well-known product of the secreting function of the liver, and is contained in man and those animals that have a gall-bladder in this reservoir and in the biliary ducts. The bile of the biliary ducts is yellowish, and more fluid than that of the gall-bladder, which last is more con- centrated, of a brownish or greenish yellow colour, a sweetish faint smell, and a decidedly bitter taste. Examined microscopically, the bile is found to con- tain epithelial cylinders detached from the gall- bladder, mucus-granules, and more rarely fat-glo- bules. The specific gravity of the bile is 1 -6352 ; it shews alkaline reaction, and contains about 10 per cent of solid matters to 90 per cent of water. The solid elements of the bile, according to Frommherz and Gugert, consist of: — Cholesterine ; Picromel (cholein mixed Avith cholesterine, according to Berzelius, about 8 per cent) ; Colouring matter ; Mucus ; Extractive matter — osmazome as well as a watery extractive of peculiar nature ; (Ptyalin ?) ; (Casein ?) ; Cholic, oleic, margaric, carbonic, phosphoric, and sul- phuric acids in combination with soda and a smaller quantity of potash ; also the phosphate, sulphate (and carbonate) of lime ; Chloride of sodium (Berzelius). Milk. — Skim-milk from the cow has, according URINE. 333 to Berzelius, a specific gravity of 1 -0348 at 60° F. The specific gravity of the cream is 1 ’0244. Skim- milk contains of Casein rendered impure by the admixture of butter 2-600 Sugar of milk 3-500 Alcoholic extractive — lactic acid and its salts 0-600 Chloride of potassium 0-170 Phosphate of potash 0-025 Phosphate of lime, lime in combination with casein ; magnesia, and traces of oxyde of iron 0-230 Water 92-875 Sour milk contains a larger quantity of lactic acid and coagulated casein. 3. The tubular glands consist of a congeries of delicate tubes, often of great length, now convoluted, now sinuous, now nearly straight, now branched frequently, now more rarely, which begin on the peripheries of the glands in blind sacs surrounded by a capillary network of vessels. These tubuli are very commonly tortuous, often they are intri- cately convoluted in their commencements ; by and by they run more directly ; through their whole course they are surrounded by capillary blood- vessels, lymphatics, and nerves. Frequently they combine and form lobuli or pyramidal subdivisions. After they have united into wider tubuli they com- bine into several or into a single efferent duct. This structure belongs to those muco-membranous glands which, like the circulating system, begin to he formed in their central and peripheral portions at once, viz. : the kidneys and the testes. The urine is principally secreted in the tubuli of 334 URINE. the cortical substance of the kidneys ; by these it is conveyed into the pelvis, from which it finds its way through the ureters into the bladder, whence it is discharged by a voluntary act through the urethra. This is essentially a watery fluid, not at all viscid, from the palest to the deepest amber colour, of a peculiar aromatic odour, and a saline taste. In specific gravity, it varies from T005 to 1*030; its reaction is acid at first, then alkaline after decom- position has commenced. Besides its ordinary or normal constituents, it is apt to contain many sub- stances accidentally taken into the stomach. The analysis of Berzelius makes human healthy urine consist of: — Water Mucus Urea Uric acid (with urate of soda and ammonia, and colouring matter) Lactic acid Lactate of ammonia I Alcoholic extractive f Watery extractive J Sulphate of potash Sulphate of soda Phosphate of soda Biphosphate of ammonia Phosphate of lime and magnesia Muriate of potash Muriate of soda Muriate of ammonia..... Fluate of lime Scilica 933-00 0- 32 30-10 1- 00 17-14 3-71 3- 16 2-94 1-65 1-00 4- 45 1-50 0-03 1000-00 SPERMATIC FLUID. 335 The urine of the horse is always turbid ; even in the pelvis of the kidney there is a commencing precipitation of minute earthy globules, which de- stroy its transparency. The spermatic fluid, whose wonderful property is to fecundate the female ovum, and so render it capable of commencing an independent existence, is of thick, almost gelatinous consistency, viscid, stringy, semi-transparent,, of a yellowish, greyish or pure white colour, and of a peculiar and often penetrating odour. It has been found to have a specific gravity of 1 '0367 ; and to consist of Water 90 Spermatine, a peculiar extractive matter 6 Phosphate of lime 3 Soda 1 100 Examined microscopically, the seminal fluid of all animals is found to contain, mingled with granular molecules and mucus-corpuscles, peculiar seminal corpuscles, which at one time appear as aggregation-corpuscles, very similar to mucus-cor- puscles and the cells of the yolk 234) ; at another, as flat granular cells, like pus-corpuscles ; farther, peculiar transparent round vesicles, which, besides their fluid contents, inclose granular cells and embryos of spermatozoa, — these may be spoken of as spermatophori ;* still farther, a multitude of * Vide Wagner, “Fragmente zur Physiologic der Zeugung,” and “ Elements of Physiology,” by Willis, Book I. ; also, Va- lentin, “ Ueber die Spermatozoen der Baren in Acta Ac. Nat. Cur.” Vol. xix. p. 1. In seminal fluid expressed from the divided substance of the human testicle, Dr. Davy invariably 336 SPERMATIC FLUID. bodies moving hither and thither amidst the fluid, and which have been long known as the sper- matozoa, or seminal animalcules ; and which, in certain species of animals, particularly in the bear, have even been believed to exhibit something like an internal organisation. The external form and internal organisation of the spermatozoa of the guinea-pig, according to my observations, are still more remarkable ; the results of these observations are embodied in the following account : — The body of the spermatozoa of the guinea-pig (fig- 231, a, a) is spoon-shaped, rounded anteriorly and at the edge, more pointed towards the tail, which is from four to five times the length of the body, and is connected with it by means of a slight enlarge- ment (, g , h, J"). Examined on the abdominal aspect, the oval papilla d is perceived in front, the aperture itself being either longer, in the shape of a slit or circular, and, posteriorly, the anal papilla e, with the rounded anal orifice. The two most anterior thirds of the body are, for the most part, occupied or made up by transparent globular vesicles (/>), which have much similarity to the stomachs of the polygastric infusoria ; the posterior third includes two rounded very finely granular organs (e), which I am inclined to regard as sexual parts. The embryo spermatozoa are found dense and apparently spherical particles, from ten to fifteen times smaller than the blood-corpuscles. I have also often seen these very minute particles in seminal fluid of the testicle. Dr. Davy conjectures that they may be the ova of the spermatozoa. “ Researches, Physiological and Anatomical,” vol. i. p. 332. — G. G. ORGAN, APPARATUS, ETC. 337 evolved in the spermatophori, as in the seminal fluid of some of the lower animals, particularly the cuttle-fish, and are found regularly applied to one another, so as to take up the least possible space {fig. 233) ; in the epididymis they may often he discovered lying together, fifteen and more in number, as they are represented in figure 233. The compound organisation of the seminal ani- malcules and their production by no equivocal ge- neration, but in particular sexual organs, and by the means of ova to all appearance, proclaims their affinity to the entozoa. As the seminal fluid that is without these animalcules is incapable of fe- cundating, their essential importance is abundantly proclaimed. And here a question might be raised as to whether or not the entozoa which, without the higher organisms they inhabit, could have no ex- istence, ought to be regarded as things necessary to these organisms ? But upon this I will not enter ; I have, however, thought it right to include figures of one or two of the forms of epizoa and entozoa, very commonly met with in many of the higher mammalia among my illustrations. Figures 229 4y and 230 are after Bremser ; figure 238 is after Raspail. ORGAN, APPARATUS, SYSTEM. § 334. Every part in an animal body which is destined for a more or less especial office is en- titled an organ, such as a muscle, the eye, the liver, the lung, &c. ; several organs which con- tribute to a common end constitute an apparatus ; z 338 ORGAN, APPARATUS, ETC, for example, the larynx, trachea, and lungs, the muscles of respiration, &c. ; apparatuses which act together to the accomplishment of a common vital object compose a physiological system, — for ex- ample, the muscular, the nervous, the circulating, the cliylopoetic, and other systems. The ana- tomical or formal systems comprehend parts having the same structure. Viscus, viscera, is the term used to designate those organs which are included in the cavities of the body. In the present day the word is restricted to the organs comprised within the thorax, abdomen, and pelvis ; the brain is scarcely spoken of now as a viscus. The various systems appertaining to an individual susceptible of an independent existence constitute an individual organism. LITERATURE OF THE GENERAL ANATOMY. CONSPECTUS. Anatomy in General. Elementary Works that in- clude the General Ana- tomy. Physiological Elementary Works that include the General Anatomy. I. General Anatomy. In general. II. Periodical works. III. Chemical constituents. IV. Elementary forms. V. Secreted fluids. VI. Inorganic precipitates. VII. Lymph. VIII. Blood. IX. Fat. X. Pigment. XI. Cells. XII. Ciliary organs. XIII. Horny system. 1. In general. 2. Cuticle. 3. Nails, hoofs, &c. 4. Hair. XIV. Cellular substance. XV. Serous system. 1. Serous membranes. 2. Synovial membranes. XVI. Tendinous system. 1. Tendinous fibres. 2. Fibrous membranes, ten- dons. XVII. Ligamentous system. XVIII. Elastic system. XIX. Cartilaginous system. XX. Osseous system. 1. In general. 2. Texture, developement, marrow. 3. Connexions. XXI. Teeth. XXII. Contractile system. XXIII. Muscular system. 1. Elementary constituents, texture. 2. Muscular power. 3. Mechanism of motion. XXIV. Nervous system. 1. The entire nervous system. 2. Nervous substance, texture. 3. Cerebro-spinal nerves. 4. Ganglionic system. XXV. Vascular system. 1. Circulation. 2. Arteries. 3. Veins. 4. Capillaries. 5. Lymphatics. XXVI. Glandular system. XXVII. Cutaneous system. 1. In general. 2. Mucous membranes. 3. Skin. XXVIII. Ovum, — Organisa- tion, and developement of elementary parts. 1. Ovum, primary organisa- tion. 2. Developement of the em- bryo. 3. Secondary organisation. XXIX. Parasites. 1. Entozoa. 2. Infusoria. 340 LITERATURE OF GENERAL ANATOMY. ANATOMY IN GENERAL. ANATOMICAL WORKS WHICH INCLUDE THE GENERAL ANATOMY. 1 M. 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Untersuch. zweier Amniosfliissigkeiten aus verschied. Perioden des Fotuslebens, in Mullers Archiv. 1837. 138 R. Marchand, liber den Harnstoff in hydropischen Fliis- sigkeiten, in Mullers Archiv. 1837. 139 Al. Donne, Recherches Microscop.^sur laNature des Mucus et de la Matihre des divers Ecoulemens des Organes Genito-urinaires. Paris, 1837. 140 Mandl, Compte Rendu de l’Acad. des Sciences, Paris. Fevr. 1837. 141 Mandl, Compte Rendu de 1’Acad. des Sciences. Sept. 1837. Gazette Medicale, 1837. L’Experience, 1838, No. 58. 142 Magnus, Vorkommen von Faserstoff in einer hydropischen Fllissigkeit, in Mullers Archiv. 1838. 143 F. Simon, liber die Corps Granuleux de Donne, in Miillers Archiv. 1838. 144 R. Marchand, liber patholog. Sekretionen im Allgemeinen, in Miiilers Archiv. 1838. 145 R. Marchand, liber die Bildung des Harnstoffs im thieris- chen Korper, in Mullers Archiv. 1839. 146 J. F. Simon, die Frauenmilch, nach ihrem chemischen und physiolog. Verhalten dargestellt. Berl. 1838, 8vo. INORGANIC DEPOSITS LYMPH. 31 9 147 J. Vogel, physiologisch-pathologische Untersuchungen iiber Eiter und Eiterbildung, und die damit verwandten Vor- gange. Erl. 1838, 8vo. 148 Henle, iiber Schleim und Eiterbildung und ihr Verhaltniss zur Oberhaut. Berl. 1838, 8vo. 149 Mandl, l’Experience, No. 79. Paris, 1839. 149* G. Gulliver, on Pus. Lond. Med. Gazette, Nov. 1839. Med. Chir. Trans, vol. xxiii. VI. INORGANIC PRECIPITATES. 150 C. F. Voelkel, Dissert, de Formatione Concrementorum Calculosorum Corp. Humani. Vratisl. 1822, 8vo. 151 J. H. F. Valentine, Dissert, de Lithogenesi. Kiliee, 1823, 4to. 152 J. H. Schmidt, Dissert, de Corporum Heterogeneorum in Plantis Animalibusque Genesi. Berol. 1825, 4to. 153 G. Jiiger, gleichartige Beschaffenheit der in der Leiche einer Frau gefundenen Gallensteine mit den 15 Jahre vor dem Tode abgegangenen, in Meckels Archiv. Bd. 6, 1832. 154 G. Valentin, iiber Bildung anorganischer Concretionen in organischen Theilen, in Mullers Archiv. 1836. 155 Schonlein, iiber Krystalle im Darmkanal bei Typhus Ab- dominalis, in Miillers Archiv. 1836. 156 G. Gluge, iiber Krystallformen in gesunden und kranken Fliissigkeiten, mit dem Mikroscope beobachtet, in Miillers Archiv. 1837. VII. LYMPH, 157 W. Hewson, Experimental Inquiries, part 2. Lond. 1764 ; and part 3, edited by Mr. Falconar. Lond. 1777. 157*P. Lassus, Dissert, sur la Lymphe. Genhve, 1774, 8vo. 158 C. G. Krause, Dissert, de Motu Chyli et Lymphae, Glandu- lisque Conglobatis. Lips. 1778, 4to. 159 C. Mayer, Chylus in den Venen des Leerdarmes, in Tiede- manns und Treviranus Untersuchungen. Bd. 1. 160 J. Muller, in Poggendorffs Annalen. 1832, Hft. 4to. 161 E. H. Weber, mikrosc. Beobachtungen iiber die sichtbare Fortbewegung der Lymphkornchen der Froschlarven, in Mullers Archiv. 1837. 350 BLOOD. 162 R. F. Marchand und Colberg, iiber die chemische Zusam- mensetzung der menschl. Lymphe, in Mullers Archiv. 1838. 163 H. Nasse, iiber die Lymphe, inTiedemanns und Treviranus Untersuch. iiber die Natur des Menschen, etc. Bd. 5. 163* G. Gulliver, On the Thymus, and on the Mesenteric and Supra-renal Glands : Dub. Med. Press, No. 52. On the Globules of the Thymus and of the Lymphatic Glands of the Camelid® : Lancet, vol. ii. 1840-41. Lymph Glo- bules of Napu Musk Deer: Lond. and Edinb. Phil. Mag. February 1840, p. 114. VIII. BLOOD. 164 Kircher, Scrutinium Physico-med. Lips. 1671. Ed. orig. Romae, 1658. 165 Wedel, Miscell. Acad. Nat. Curios. Dec. 2, ann. 5, 1686, p. 788. 166 A. Leeuwenhoeck, Arcana Nat. Detecta, etc. 167 Jurin, Philos. Transact. 1717, No. 355. 168 W. G. Muys, Investigate Fabric®, quae in Partibus Musculos componentibus exstat. Ludg. Bat. 1741, 4to. 169 Menghini, de Bononiensi Scientiarum Instit. Comment. Bon. 1746. 170 Senac, Traite du Cosur. Paris, 1749. Tom. 2. 171 Weiss, Acta Helvet. vol. iv. et v. Basil. 1760. 172 Della Torre, N. Osservaz. Micr. 173 W. Hewson, Experimental Inquiries into the Properties of the Blood, parts 1 , 2, and 3. Lond. 1771-8, 8 vo. Opus Posthum. ed. Mr. Falconar, Lat. vertit J. Th. van der Wvnpresse. L. B. 1785, 8vo. 174 Torre, Epist. ad Haller (1759). Bern®, 1774. 175 Fontana, i Globetti del sangue. Luce. 1766. 175*Piorry et l’Heritier, Traite des Alterations du Sang, 8vo. Paris, 1840. 176 Spallanzani, del Azione del Cuore ne Vasi sanguinee. Modena, 1768. 177 Magni, Nuove Osservaz. Micr. sopra le Molec. Rosse del Sangue. Mil. 1776. 178 G. Levison, Versuch iiber das Blut. Berl. und Stettin, 1782, 8vo. 179 F. Fontana, sur le Venin de la Vipere, etc. 180 Poli, Testacea utriusque Silici®. Parrn®, 1792. BLOOD. 35 1 181 J. Hunter, Treatise on the Blood, Inflammation, and Gun- shot Wounds. Lond. 1794, 4to. Deutsch von F. B. G. Hebenstreit. Leipz. 1797-1800. 2 Bde. 8vo. 182 Caldani, Memorie di Padova. 1794, tom. iii. part 1. 183 Villars, Journal de Physique, tom. lviii. Paris, 1804. 184 F. P. von Gruithuisen, Beitrage zur Physiognosie und Eautognosie. Miinchen, 1812, 8vo. 185 G. R. Treviranus, iiber die organ. Elemente des thierischen Korpers, in verm. Schriften. Bd. 1. 186 E. Home and F. Bauer, in Philos. Transact. 1818, 1820. 187 J. C. L. Schroder van der Kolk, Dissert, sistens Sanguinis Coagulantis Historiam. Gron. 1820, 8vo. 188 Young, Introduction to Medical Literature, 8vo. Lond. 1813. 2d edit. 1823. 189 Prevost et Dumas, in Magendie, Journal de Physiologie et Biblioth&que Universelle, 1821. 190 Dollinger, in Denkschr. der. k. baier. Akad. der Wissensch. 1821, VII., und in d. neuen Denkschr. 1835. 191 Schmidt, iiber die Blutkorner. Wiirzb. 1822. 192 Dalle Chiaje, Mem. sulla Storia degli Anim. senza Ver- tebre. Nap. 1823. 193 C. Williams, Observat. on the Changes produced in the Blood. . Edinb. 1823, 8vo. 194 J. C. Schmidt, iiber die Blutkorner. Zurich, 1823, 4to. 195 C. F. Koch, Dissertatio de Observat. Nonnullis Microsco- picis Sanguinis Cursum et Inflammationem Spectantibus, atque de Suppuratione ; adjecta Analysi Puris Chemica. Berol. 1825, 8vo. 196 C. H. Schulz, Bemerkungen iiber Blutbildung und Blut- bewegung, in Meckels Archiv. 1827. 197 Hodgkin and Lister, in Philosophical Magaz. &c. 1827. 198 P. S. Denis, Recherches Experimentales sur le Sang Humain. Paris, 1830, 8vo. 199 G. A. Lauer, Diss. Quaedam de Sanguinis Differentia in Morbis. Ber. 1830. 200 K. H. Baumgartner, iiber die Nerven und das Blut. Freib. 1830, 8vo. 201 J. Muller, in Poggendorfs Annalen der Physik und Chemie, 1832, Hft. 8 vo. Burdach’s Physiol. Bd. 4. 202 Edwards, Ann. des Sciences Nat. Paris, 1826. Todd, Cyclopaedia. Lond. 1836. 203 Czermack, Medicinische Jahrbucher des ostreich. Staates. 1831. 352 BLOOD. 204 Donne, Recherches sur les Globules du Sang, th&se No. 8. Paris, 1831. 205 H. Nasse, mikroscop. Beobachtungen iiber die Bestandt- heile des Blutes und der sich zur Faserhaut gestal- tenden Fllissigkeit, in Untersuchungen der Physiol, und Pathol, von Fr. und H. Nasse. Erstes Hft. Bonn, 1825, 8 vo. 206 Mandl, Sanguis Respectu Physiologico. Pesth, 1836. 207 E. Mitscherlich, Versuche iiber das Blut. Gmelin u. Tiede- mann. Bd. 5. 208 Lecanu in Annales de Chimie et de Physique, tome xlviii. Paris, 1831. Poggendorf Annalen, 1832. Heft 4. 209 C. F. Koch, iiber die Entziindung, nach mikrosc. Ver- suchen, in Meckels Archiv. Bd. 6, 1832. 210 J. Heinemann, Diss. de Motibus qui ante et inter Coagu- lationem Sanguinis per Microscopiam observantur : Addita sunt qusedam de Vita Sanguinis. Regiomont. 1832, 8vo. 211 A. Richters, das Blut u. der Blutumlauf d. Menschen. Wiirzb. 1834, 8vo. 212 C. F. Emmert, Diss. Observat. qusedam Microscopic® in Partibus Animalium Pellucidis Institute, et de Inflamma- tione. Berol. 1835, 8vo. 213 L. Bruener, Diss. de Vesicularum Sanguinis Natura, Ob- servat. Microscopic® et Chemic®. Berol. 1835, 8vo. 214 R. Wagner, Beitrage zur vergleich. Physiol. Erstes Heft, zur vergleich. Physiol, des Blutes. Leipz. 1833, 8vo. Heft 2, 1838. 215 L. Lecanu, Etudes Chim. sur le Sang Humain. Paris, 1837, 4to. 216 G. Valentin, Repert. fur Anatomie und Physiologic. Berl. 1836, Hft. 1. 217 Schulz, System der Cirkulation. Stuttg. 1836. Hufelands Journ. 1838. 218 Magendie, Leqons sur les Phenom. Phys. de la Vie. Tom. iv. Lecons sur le Sang. Paris, 1838, 8vo. 219 C. G. Mitscherlich, einige Bemerkungen iiber die Veran- derungen, welche das Blut durch Arzneimittel erleidet, in Mullers Archiv. 1838. 220 Mandl, l’lnstitut. 1836, No. 189, b; 1837, No. 194, c. Gazette Medic. 1837, No. 40. 220* J. Davy, Researches Physiological and Anatomical, 2 vols. 8vo. Lond. 1839. FAT. 353 221 G. Gulliver, on Pus in the Blood : Lond. and Edinb. Phil. Mag. for September 1838. On the Blood-Corpuscles of Mammals : ibid, for January, February, March, August, and November 1840. Corpuscles of Camelidse : Med. Chir. Trans, vol. xxiii. ; Lancet, vol. ii. 1140-41, p. 101. Corpuscles of the Passenger Pigeon and Snowy Owl : Proc. Zool. Soc. May 26, 1840. Corpuscles of the Cro- codilidas : ibid. November 10. Corpuscles of the Com- mon Paradoxure : ibid. November 24. Corpuscles of Ferae: ibid. May 25, 1841. Corpuscles of Marsupials : ibid. June 28, 1841. On the Softening of Fibrine: Med. Chir. Trans, vol. xxii. Organic Germs in and Va- rieties of Fibrine : Dub. Med. Press, Nos. 119 and 121. On Milky or Chylous Serum: ibid. No. 120. On the Blood-Corpuscles of Mammalia and Birds: Appendix to Gerber’s General Anatomy. On the Structure of Fibrine: Note to § 31, p. 28, ibid. 221*Ancell, Lectures on the Blood : Lancet, 1840-41. Queckett, in Microscopic Journal, vol. i. 1841. IX. FAT. 222 W. Hunter, Remarks on the Cellular Membrane in Med. Observations and Inquiries by a Society of Physicians in London. Vol. ii. 223 Th. Bordeu, Recherches sur le Tissu Muqueux. Paris, 1767, 12mo. Deutsch, Wien and Leipz. 1772, 8vo. 224 C. F. Wolff, de Tela quam dicunt Cellulosa, in Nova Acta Acad. Scient. Petropol. tom. vi. vii. viii. 225 Lorry, sur la Graisse dans le Corps Humain, in Memoires de la Soc. Roy. de Medecine, 1779. Deutsch von Lindemann. Berl. 1797, 8vo. 226 F. Fontana, Traite sur le Venin de la Viphre, avec Ob- servat. sur la Structure Primitive du Corps. Animal. Florence, 1781, 4to. 227 W. X. Janssen, Pinguedinis Animalis Consideratio Phys. et Pathol. Ludg. Bat. 1784. Uebers. von Jonas. Halle, 1786, 8vo. 228 S. C. Luca, in Reils Archiv. Bd. 9. 229 Heusinger, System der Histologie. Thl. I. Eisenach, 1822. 230 C. H. E. Allmer, Dissert. Inaug. sistens Disquisitiones Anat. Pinguedinis Anim. Jente, 1823, 4to. 231 O. B. Kuhn, de Pinguedine Imprimis Humana. Lips. 1825, 4to. A A 354 PIGMENT, CELLS, ETC. 232 Raspail, Recherches Physiol, sur les Graisses et le Tissu Adipeux, in Repert. d’Anat. et de Physiol. Pathol. 1827. X. PIGMENT. 233 H. F. Elssesser, Dissert, de Pigmento Oculi Nigro, de Atramentis aliis Quibusdam Animalibus deque Tapeto. Tub. 1800, 8vo. 234 C. F. Heusinger, iiber Kohlen- und Pigmentbildung. 1823. 8vo. XI. CELLS. 235 M. J. Schleiden, Beitr. zur Phytogenesis, in Mullers Archiv. 1838. 236 Th. Schwann, mikrosc. Untersuchungen iiber die Ueberein- stimmung in der Struktur und dem Wachsthum der Thiere u. Pflanzen. Berl. 1839, 8vo. XII. CILIA AND CILIARY ORGANS. 237 Purkinje et Valentin, de Phsenomeno Gen. et Funda- mental!, &c. Vratisl. 1835. 238 Purkinje und Valentin, iiber die Unabhangigkeit der Flim- merbewegungen der Wirbelthiere von der Integritat des centralen Nervensystems, in Mullers Archiv. 1835. 239 Purkinje, iiber Flimmerbewegungen im Gehirn, in Mullers Archiv. 1836. 240 G. Carus, neue Beobachtungen iiber das Drehen des Em- bryo im Ei der Schnecken (Nova Acta A. C. L. V. XIII. P. II.) 241 Sharpey, in Cyclopaedia of Anatomy and Physiology, sub voc. XIII. HORNY SYSTEM. 1. IN GENERAL. 242 K. A. Rudolphi, iiber Hornbildung, in Abhandl. der Akad. der Wissenschaften zu Berlin. 1814-15. 243 C. F. Heusinger, System der Histologie. Eisenach, 1822, 4to. Heft 2. 244 M. A. Unna, de Tunica Humoris Aquei Commentatio Anat.-Physiol. et Pathol, (praemio ornata). Heidelb. 1836, 8vo. HORNY SYSTEM. 355 245 G. R. Treviranus, liber die blatterige Textur der Krystal- linse des Auges als Grund des Vermogens einerlei Gegenstand in verschiedener Entfernung deutlich zu sehen u. liber den innern Bau der Retina. Brem. 1835, 8vo. 246 Gurlts und Hertwigs Mag. f. d. gesammte Thierheilkunde. Bd. 1. 1836. 247 Gurlt, Untersuchungen liber die hornigen Gebilde des Menschen und der Haussaugethiere, 1836. Miillers Archiv. 1835. 248 Meier-Ahrens, Bemerkungen liber die Struktur der Linse, in Mullers Archiv. 1838. 2. CUTICLE, EPIDERMIS. 249 M. Malpighi, Opera Omnia, &c. 250 A. Leeuwenhoeck, Arcana Naturae detecta, &c. 251 J. F. Meckel, sen., sur la Nature de l’Epiderme et du Re- seau Malpighien, in Hist, de l’Acad. Roy. des Sciences de Berlin. 1753. 252 J. B. Morgagni, de Cuticulse Natura et Generatione, L. II., in Advers. Anat. Patav. 1706-19, 4to. Ven. 1762, fol. 253 C. G. Ludwig, Diss. de Cuticula. Lips. 1739, in Haller, disp., vol. iii. 254 A. Monro II., de Cuticula Humana, in A. Monro I. works. Edinb. 1781, 4to. 255 B. S. Albinus, de Cuticula, de Reticulo, in Annot. Acad. L. LVII. 256 Cruikshank, Experiments on the Insensible Perspiration of the Human Body. Lond. 1779 and 1795, 8vo. Deutsch, von Michaelis. Leipz. 1798, 8vo. 257 E. H. Weber, Beobacht. liber die Oberhaut, Hautbalge und iiber die Haare des Menschen, in Meckels Archiv. f. Anat. u. Physiol. 1827. 258 B. S. Albin, de Sede et Causa Coloris iEthiopum. Lugd. Bat. 1737, 4to. and in Annot. L. I. 259 C. N. Le Cat. Traite de la Couleur de la Peau Humaine, &c. Amst. 1765. 260 P. Camper, liber die Farbe der Schwarzen, in dessen kleinen Schriften, libers, von Herbell. Bd. I. Lpz. 1782, 8vo. 261 J. F. Blumenbach, de Generis Hum. Varietate Nativa. Ed. 356 HORNY SYSTEM. Tert. Gaett. 1795, 8vo. Trad, en Franqais, 8vo. Paris, 1808. 262 S. Th. Sbmmering, liber die korperl. Verschiedenheit des Negers vom Europaer. Mainz, 1784, 8vo. 263 E. Home, liber das schwarze Schleimnetz der Neger, in Meckels deutsch. Arcbiv. Bd. 8. 264 W. Lawrence, Lectures on Physiology, & c. Lond. 1819, 8vo. 265 F. Lelut, Etudes Anat. sur l’Epithelium, in Repert. d’Anat. et de Physiol. Pathol. 1827. 266 A. Wendt, Dissert, de Epidermide Humana. Vratislav. 1833, 4to. 267 A. Wendt, liber die menschl. Epidermis. Mullers Archiv. 1834. 268 Henle, liber die Ausbreitung des Epitbelum im mensch- lichen Korper, in Mullers Archiv. 1838. 3. NAILS. 269 C. G. Ludwig, Comment, de Ortu et Structura Unguium. Lips. 1748, in Haller Disp. vol. vii. 270 B. S. Albinus, de Ungue Hum. &c. in Annot. Acad. L. II. 271 J. G. Haase, Experimenta Anatom, ad Nutritionem Un- guium declarandam. Lips. 1774, 4to. 272 C. F. Nlirnberger, Meletemata super Digitorum Unguibus. Viteb. 1798, 4to. 273 F. A. Frenzel, Unguium et Pilorum Corporis Humani Dis- quisitiones Anatomic®, Physiologic® et Pathologic® ad Nonnullorum Morborum Prognosis Stabiliendam. Vra- tisl. 1822, 8vo. 274 J. G. Sinds, Dissert, de Unguibus Hum. Landish. 1825, 4to. 275 A. Besserer, Dissert. Observat. de Unguium Anat. et Pa- thol. Bonn®, 1834, 8vo. 276 L. O. Lederer, Diss. de Unguib. Hum. Berol. 1834, 8vo. 277 A. Cooper, Observations on the Anatomy and Diseases of the Nails, in Lond. Med. and Phys. Journal, 1827. 4. HAIR. 278 A. de Leeuwenhoeck, in Op. Omn. 279 B. S. Albinus, in Annot. Acad. L. IV. 280 J. P. L. Withof, de Pilo Hum. Duisb. 1750, 1752, and in Comment. Reg. Soc. Goett. t. III. 1753. CELLULAR SUBSTANCE. 357 281 J. G. Kniphof, de Pilorum Usu, in Comment, de Reb. &c. Lips. Vol. IV. pars 1. Deutscb, Rotenburg, 1777, 8vo. 282 J. F. Pfaff, de Variet. Pilorum. Halse, 1799, 4to. 283 J. F. W. Richter, Comment, de Pilo Hum. Goett. 1800, 8vo. 284 K. A. Rudolphi, Hiss, de Pilorum Structura. Gryphsw. 1806, 4to. 285 A. Rowlandson, Essay on the Human Hair. Lond. 1818, 8vo. 286 H. G. Buek, Diss. de Pilis Eorumque Morbis. Halse, 1819, 8vo. 287 C. F. Heusinger, liber die Haaren, &c., in Meckels deutsches Archiv. Bd. 7, 8. 288 E. H. Weber, in Meckels Archiv. fur Anat. u. Physiol. 1837. 289 C. Girou de Buzareingues, Mem. sur les Pods, in Brechet’s Repert. t. VI. 1828. 290 Meier Bendix, Diss. de Pilis Corp. Hum. Berol. 1829, 8vo. 291 B. Eble, die Lehre von den Haaren. Wien, 1831, 2 Bde. 8vo. Fig. 292 B. C. Trinius, liber das Wesen und die Bedeutung der menschl. Haare und Za'hne. Acta Acad. C. L. V. XVIII. 293 C. J. A. Bceck, Diss. de Spinis Histrionum. Berol. 1834, 4to. 294 Esehricht, liber die Richtung der Haare am menschl. Korper, in Miillers Archiv. 1837. XIV. CELLULAR SUBSTANCE. 295 W. 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Liepz. 1824, 8vo. 501 Tiedemann, iiber Regeneration der Nerven, in Tiedemann und Treviranus Untersuchungen, etc. Bd. 4. 502 G. Spurzheim, the Anatomy of the Brain and Nervous System, from the unpublished French MS. by R. Willis, M.D. Lond. 1826, 8vo. 503 J. Miiller, iiber die Metamorphose des Nervensystems und der Thierwelt, in Meckels Archiv. 1828. 504 K. H. Baumgartner, Beobachtungen iiber die Nerven und das Blut in ihrem gesunden und krankhaften Zustande. Freiburg, 1830, 8vo. 505 C. Bell, Natural System of the Nerves: Lond. 1824, 8vo. Appendix to Papers on the Nerves: ibid. 1827. 8vo. The Nervous System of the Human Body, 4to. : Lond. 1830. Third edition, 8vo. 1836. Three Papers on the Nerves of the Encephalon, Trans. Royal Society of Edinb. 1838. 505* A. Shaw, Account of the Discoveries of Sir Charles Bell in the Nervous System. Lond. 1839, 8vo. 506 C. Holle, Diss. de Nervorum Systemate qusedam generalia. Berol. 1833, 8vo. 507 C. O. Steinrueck, Dissert, de Nervorum Regeneratione. Berol. 1838, 4to. B B 370 NERVOUS SYSTEM. 508 J. Swan, Demonstrations of the Nerves of the Human Body, fol. Lond. 1830. Ejus , Comparative Anatomy of the Nervous System, 4to. 1835-41. Neurologie, ou De- scription Anatomique des Nerfs du Corps Humain, trad, de l’Angl. avec des Add. par E. Chassaignac. Paris, 1 838, 4to. 509 F. Arnold, Bemerkungen liber den Bau des Hirnes und Ruckenmarks. Zurich, 1838, 8vo. 510 Ehrenberg,Poggendorf’s Annalen derPhysik, 1838. Bd.28. 511 Krause, Poggendorf’s Annalen, 1834. Bd. 31. 512 Berres, med. Jahrb. des ostreich. Staates, 1834. Bd. 9. 513 Lauth, l’lnstitut, 1835. 514 Wagner, in Burdach’s Physiol. Bd. 5, 1835. 515 S. Solly, the Human Brain, &c. 12mo. Lond. 1836. 516 F. le Gros Clark, Anatomy of the Brain and Nervous System. 12mo. Bond. 1836. 517 Schwann, Mullers Archiv. 1836, Jahresber. 518 Mullers Archiv. 1837, Jahresber. 519 Volkmann, neue Beitr. zur Physiol, des Gesichtssinnes. 520 Treviranus, Beitr'age zur Aufklarung des organ. Lebens. Bremen, 1836. Hft. 2. 521 Remack, Mullers Archiv. 1836. S. 145. 522 Weber, Mullers Archiv. 1837. 523 Steinriick, de Nervorum Regeneratione. Berol. 1838, 4to. 524 G. Valentin, de Functionibus Nervorum Cerebralium et Nervi Sympathici. Bernee et Sangalli, 1839, 4to. 524* Hall (Marshall), on the Diseases and Derangements of the Nervous System, 8vo. with 8 plates. Lond. 1841. 2. nervous matter; texture of the brain and nerves. 525 M. Malpighi, de Cerebri Cortice, in Operib. omn. Lond. 1686, fol. And in Manget, Bibl. anat. tom. ii. 526 A. a Leeuwenhoeck, Arcana Nat., etc. 527 G. L. Teissier, de Substantia Corticosa et Medullosa Cerebri. Lugd. Bat. 1710, 4to. 528 M. E. Ettmiiller und F. Ruysch, in F. Ruysch, Op. omn. 529 J. F. Isenflamm, de Vasis Nervorum. Erl. 1768, in Ludwig, Script. Neurol. Min. tom. iii. 530 G. Prochaska, de Structura Nervorum. Vind. 1779. Op. min. vol. i. NERVOUS SYSTEM. 371 531 C. F. Ludwig, de Cinerea Cerebri Substantia, in Exercit. Acad. Lips. 1779, 8vo. fasc. 1. 532 J. Pfeffinger, de Struct. Nervorum. Argent. 1782-3, 4to. And in Ludwig, Script, tom. i. 533 A. Monro II., Observat. on the Nervous System. Edinb. 1783, fol. 534 F. Fontana, sur le Venin de la Vip&re, etc. 535 J. C. Reil, Exercit. Anat. fasc. i. Hal. 1795, fol. 536 A. Barba, Osservazioni Microscopiche sull’ Cervello e sue Parti adjacenti. Nap. 1807, 4to. Iterum, 1819. Deutsch von A. v. Schonberg. Wiirzb. 1829, 4to. 537 G. R. Treviranus, iiber die organ. Elemente des thierischen Korpers, etc. 538 E. Home, Exp. and Obs. upon the Structure of Nerves, in Philos. Transact. 1799, 1822. On the Internal Struc- ture of the Hum. Brain. Ibid. 1824. 539 Prevost et Dumas, in Magendie, Journal, etc. tom. iii. 1823. 540 E. Milne Edwards, Mem. sur la Structure F.lem. des Nerfs, 541 Hodgkin and Lister, in Philosophical Magaz. &c. Annals of Philosophy, Aug. 1827. 542 J. A. Bogros, Mem. sur la Structure des Nerfs, in Breschet, Repert. vol. iv. Heusingers Zeitschrift, Bd. 2. 543 G. Breschet et Raspail, Anatomie Microscop, des Nerfs, in Breschet, Repert. tom. iv. Heusingers Zeitsch. Bd. 2. 544 J. A. Bogros, Mem. sur la Struct, des Nerfs, in Repert. Gen. d’Anat. et de Physiologie Pathol, etc. 1827. 545 Breschet et Raspail, Anat. Microsc. des Nerfs pour De- montrer leur Structure Intime et l’Absence de Canaux contenant un Fluide et pouvant apres la Mort etre facilement Injectes, in Repert. Gen. d’Anat. etc. 1827. 546 F. Rosenthal, in Frorieps Notizen, 1830. 547 J. van Deen, Disquisitio Physiol, de Differentia et Nexu inter Nervos Vitae Animalis et Vitae Organicae. L. B. 1834, 8vo. 548 H. Kronenberg, Experimenta in Ran® Esculent® Plexu Lumbali facta, Veram Nervorum Fibrillarum, quas Pri- mitivas vocant, Anastomosin refellentia. Diss. Berol. 1835. 549 G. R,. Treviranus, iiber die blattrige Textur der Krystall- linse des Auges, als Grund des Vermogens einerlei Gegenstand in verschied. Entfernung deutlich zu sehen und iiber den innern Bau der Retina. Brem. 1835, 372 NERVOUS SYSTEM. 550 C. G. Ehrenberg, Beobachtung einer auffallenden, bisher unbekannten Struktur des Seelenorganes bei Menschen und Thieren. Berl. 1836, fol. 551 G. Valentin, liber den Verlauf und die letzen Enden der Nerven, 1836, 4to. (Acta Acad. C. L. vol. xviii. pt. 1.) 552 H. Kronenberg, Plexuum Nervor. Struct, et Virtutes. Berol. 1836, 8vo. 553 F. C. Emmert, liber die Endigungsweise der Nerven in den Muskeln. Bern, 1836, 4to. 554 E. Burdach, Beitr. zur mikroscop. Anat. der Nerven. Konigsb. 1837, 4to. 555 R. Remak, Observ. Anatom, et Microscop, de Systematis Nervosi Structura. Berol. 1837, 4to. 556 A. W. Volkmann, liber die Faserung des Riickenmarkes und des sympathischen Nerven in Rana Esculenta, in Mullers Archiv. 1838. 557 C. Mayer, die Elementarorganisation des Seelenorganes. Bonn, 1838, 4to. 3. CEREBRO-STIN AL NERVES. 558 J. J. Huber, Pr. de Medulla Spinali, speciatim de Nervis ab ea provenientibus. Goett. 1741, 4to. 559 F. Magendie, in Journal de Physiologie Experimentale, tom. ii. 1822. Meckels deutsch. Archiv. Bd. 7. 560 C. F. Bellingeri de Medulla Spinali Nervisque ex ea Pro- deuntibus Annotationes Anat. Phys. Aug. Taur. 1823, 4to. 561 Ch. Bell, an Exposition of the Natural System of the Nerves of the Human Body: Lond. 1824, 8vo. On the Nervous Circle which connects the Voluntary Muscles with the Brain, in Philos. Transact. 1826. Lectures on the Nervous System, in Lond. Med. Gazette, 1828. Karl Bell, Anat. Physiol. Abhandl. liber das Nerven- system, libers, von M. H. Romberg. Berl. 1832, 8vo. Vide No. 505. 562 C. G. Schops, liber die Verrichtungen versch. Theile des Nervensystems, in Meckels Archiv. fur Anat. u. Physiol. 1827. 563 J. Muller, in Frorieps Notizen. 1831, Marz. 564 B. Panizza, in Annali Universali di Medicina, 1831. Maggio e Giugno. 565 Steifensand, Untersuchungen liber die Ampullen des Ge- hororganes, in Mullers Archiv. 1835. NERVOUS SYSTEM. 373 566 R. Remak, vorlaufige Mittheilung mikroscop. Beobach- tungen liber den innern Bau der Cerebrospinalnerven und liber die Entwicklung ihrer Formelemente, in Mlillers Archiv. 1836. 567 A. W. Volkmann, anat. Notizen zum Bau der Sehnerven und der Netzhaut, in neue Beitrage zur Physiol, des Gesichtssinnes. Leips. 1836, 8vo. 568 G. Breschet, Recherches Anat. et Physiol, sur l’Organe de l’Audition. Paris, 1836, 8vo. 569 D. G. L. Girgensohn, Bildungsgeschichte des Riickenmark- systems, mit Bezug der allg. Bildungsgesch. Riga u. Leipz. 1837. 570 G. R. Treviranus, Resultate neuer Untersuchung. liber die Theorie des Sehens u. liber den innern Bau der Netzhaut des Auges. Brem. 1837,- 8vo. 571 Shaw, Narrative of the Discoveries of Sir Charles Bell in the Nervous System. Lond. 1839, 8vo. 572 An Historical Account of the Discoveries made in the Anatomy and Physiology of the Nervous System. Lond. 8vo. 1840. 4. GANGLIONIC SYSTEM. 573 J. M. Lancisi, de Structura Usuque Gangliorum ; in Mor- gagni Adversar. Anat. Patav. 1706-19. 574 J. G. Haase, Diss. de Gangliis Nervorum. Lips. 1772 ; in Ludwig, Script. Neur. tom. i. 575 J. Johnstone, Essay on the Use of the Ganglions of the Nerves. Shrewsbury, 1771, 8vo. Deutsch : Stettin, 1787, 8vo. Also in Medical Essays and Observ. with Disquisitions relative to the Nervous System. Lond. 1795, 8vo. Deutsch von Michaelis. Leipz. 1796, 8vo. 576 E. H. Weber, Anat. Comparata Nervi Sympath. Lips. 1817. 577 J. F. Lobstein, de Nervi Sympathici Humani Fabrica, Usu et Morbis. Paris, 1813, 4to. 578 J. C. Reil, iiber die Eigenschaften des Gangliensystems und sein Verhaltniss zum Cerebralsvstem, in Reils Archiv. Bd. 7. 579 K. 4. Rudolphi, einige Bemerk. liber den sympath. Nerven, in Abhandl. der k. Akad. der Wissensch. in Berlin, fur die Jahre, 1814 u. 1815. 580 C. G. Wutzer, de C. H. Gangliorum Fabrica atque Usu. Beroi. 1817, 4to. 374 GENERAL VASCULAR SYSTEM. 581 J. L. Brachet, Memoire sur les Fonctions du Syst&me Nerveux Ganglionnaire. Paris, 1823, 8vo. 582 F. Tiedemann, uber den Antheil des sympath. Nerven an den Verricht. der Sinne, in dessen Zeitschr. fur Physiol. Bd. 1. 583 F. Arnold, der Kopftheil des vegetativen Nervensystems beim Menschen, in anat. und physiol. Hinsic.ht bearbeitet. Heidelb. 1830, 4to. 584 A. Scarpa, de Nervorum Gangliis et Plexubus ; in Annotat. Anat. Lib. 1. De Gangliis Nervorum deque Origine et Essentia Nervi Intercostalis, ad E. H. Weberum. Mil. 1831, 8vo. 585 J.L. Brachet, Recherches Experimentales sur les Fonctions du Systhme Nerveux Ganglionnaire. Paris, deuxihme edit. 1837, 8vo. XXV. GENERAL VASCULAR SYSTEM. 1. CIRCULATION. 586 G. Harveei Exercitatio Anat. de Motu Cordis et Sanguinis Circulatione in Animalibus. Fcf. 1628, 4to. 587 St. Hales, Statical Essays. Lond. 1731-33, 2 vol. 8vo. Haemastaticks. Framjais par Sauvages. Geneve, 1744, 4to. , 588 J. B. Senae, Traite de la Structure de Coeur, de son Action et de ses Maladies. Paris, 1749, 4to. Dass. 1744, 4to. 589 F. Boissier de Sauvages, Pulsus et Circulationis Theoria. Monsp. 1752, 4to. 590 A. de Haller, deux Mem. sur le Mouvement du Sang. Laus. 1756, 12mo, et in Elementa Physiol. 591 G. Verschuir, de Arteriarum et Venarum Vi Irritabili, etc. Gron. 1766, 4to. 592 L. Spallanzani, dell’ Azione del Cuore n’e Vasi Sanguigni. Mod. 1768, 4to. Dei Fenomeni della Circolazione. Mod. 1777, 8vo. 593 G. Prochasca, Op. Min. Vien. 1800, 8vo. 594 Th. Young, on the Functions of the Heart and the Arteries, in Philos. Transact. 1809. 595 C. ILillier Parry, Experimental Inquiry into the Nature, Cause, and Variety of the Pulse, and certain other Pro- perties of the larger Arteries. Lond. 1816, 8vo. Deutsch von Embden. Hannov. 1817, 8vo. Also Additional Experiments. Lond. 1819, 8vo. GENERAL VASCULAR SYSTEM. 3J 5 595* C. Bell, on the Forces which Circulate the Blood. Lond. 1819, 12mo. 596 C. Hastings, de Vi Contractili Vasorum. Edinb. 1818, 8vo. and in his Treatise on the Inflammation of the Mu- cous Membrane of the Lungs. Lond. 1820, 8vo. Deutsch von G. v. Busch. Bremen, 1822, 8vo. 597 C. G. Carus, liber den Blutlauf, in wie fern er durch die Druck- und Saugkraft des Herzens bewirkt wird, in Meckels Archiv. Bd. 4. 598 M. Jaeger, de Arteriarum Pulsu. Virceb. 1820, 8vo. 599 C. W. L. Jaeckel, de Motu Sanguinis. Vratisl. 1821, 4to. 600 Ph. Hensler, neue Lehren im Gebiete der physiol. Ana- tomie und der Physiologie des Menschen. Bd. 1, von den feinsten Verbindungen der verschiedenen Gefass- systeme (Arterien, Venen und Lymphgefasse) unter sich und von ihren letzten freien Endigungen. Nlirnb. 1825, 8 vo. 601 J. H. Destereicher, Bersuch einer Darstellung der Lehre vom Kreislaufe des Blutes. Nurnb. 1826, 4to. 602 D. Barry, Experimental Researches on the Influence ex- ercised by Atmospherical Pressure upon the Progression of the Blood in the Veins. Lond. 1826, 8vo. 603 C. H. Schulz, iiber Blutbildung und Blutbewegung, in Meckels Archiv. fur Anat. u. Physiol. 1826. 604 L. F. Koch, ist die Contraktion des Herzens die einzige bewegende Kraft des Blutumlaufs u. s." w. ? in Meckels Archiv. 1826. 605 H. F. Bonorden, Beitrag zur Lehre von der Blutbewegung, in Meckels Archiv. 1826. 606 G. Wedemeyer, Untersuch iiber den Kreislauf des Blutes. Hann. 1828, 8vo. Erganzungen in Meckels Archiv. 1828. 607 Poiseuille, sur la Force du Cceur Aortique ; sur l’Action des Arteres, in Breschet, Repertoire, 1829. 608 C. Mayer, gehen Fliissigkeiten wahrend dem Leben aus den Arterien in die Venen iiber? Ein Beitrag zur Physiol, des Kreislaufs, in Tiedemann und Treviranus Untersuch. etc. Bd. 3. 609 Hering, Versuche die Schnelligkeit des Blutlaufs und der Absonderungen zu bestimmen, in Tiedemann u. Tre- viranus Untersuch, etc. Bd. 3. 610 J. Barkow, Diss. Disquisit. nonnullae Angiologicae. Vratisl. 1830, 4to. 376 GENERAL VASCULAR SYSTEM. 611 Marshall Hall, a Critical and Experimental Essay on the Circulation of the Blood. Lond. 1831, 8vo. 612 W. P. Gruithuisen, liber die Daphnia sima und ihren Blutkreislauf. Nova Acta Phys. Acad. C. L., tom. xiv. p. 1. 613 M. Gerdy, Circulation. Paris, 1834, 8vo. 614 K. E. v. Baer, liber das Gefasssystem des Braunfisches (Akad. v. Berl. 1834), 4to. 615 A. Richters, das Blut und der Blutumlauf des Mensch. Wiirzb. 1834, 8vo. 616 E. Chasseignac, le Cceur, les Artkres et les Veines. Paris, 1836, 8vo. 617 C. H. Schulz, das System der Cirkulation in seiner Ent- wickelung durch die Thierreiche u. im Menschen. Stuttg. u. Tiib. 1836, 8vo. 618 F. M. Ascherson, iiber die relative Bewegung der Blut- und Lymphkornchen in den Blutgefassen der Frosche, in Mullers Archiv. 1837. 619 Krause, vermischte Beobachtungen u. Bemerk. in Miillers Archiv. 1837. 620 G. Valentin, iiber den Verlauf der Blutgefasse des Penis des Menschen u. einiger Saugethiere, in Miillers Archiv. 1838. 621 E. H. Weber, iiber die in den Adern lebender Frosche und Froschlarven sichtbare Bewegung von Kornchen,Avelche die Gestalt der Lymphkornchen haben, iiber die Gesch- windigkeit mit welcher sie sowohl als die Blutkor- perchen in den Haargefassen sich bewegen, in Mullers Archiv. 1838. 622 R. Wagner, Beitrage zur vergleich. Physiol. Heft I. und II. Leipz. 1838, 8vo. 623 M. Roberts, on the Analogy between the Electric and Nervous Influences, in Lond. Ed. and Dub. Philos. Journ. July 1841. 2. ARTERIES. 624 J. H. Hebenstreit, de Arteriarum Corp. Hum. Confiniis. De Vaginis Vasorum. De Flexu Arteriarum, in Haller, Disput. Anat. quas collegit et edidit, vol. i. Gcett. 1746-51, 7 vol. 625 B. S. Albinus, de Arterise Membranis et Vasis, lib. iv. in Annotat. Academ. lib. viii. Leid. 1754-68, 4to. 626 A. Monro I., on the Coats of the Arteries, in works. Edinb. 1781, 4to. GENERAL VASCULAR SYSTEM. 377 627 J. Hunter, Treatise on the Blood, Inflammation, and (Tun- shot Wounds. Lond. 1794, 4to. Deutsch von E. G. B. Hebenstreit. Leipz. 1797-1800, 2 Bde. 8vo. 628 J. F. S. Posewitz, Physiol, der Pulsadern des mensch. 1 Till. Leipz. 1795, 8vo. 629 H. A. Wrisberg, de Nervis Arterias Venasque comitantibus, in Comment. Med. etc. Goett. 1800, 8vo. 630 S. C. Luca, liber die Nerven, die zu den Arterien gehen, in Reils Archiv. Bd. 9. 631 J. F. Meckel, liber den Verlauf der Arterien u. der Venen, im deutsch. Archiv. Bd. 1. 632 F. Ribes, Untersuch., in Meckels deutsch. Archiv. Bd. 5. 633 C. Th. Rainarz, Diss. de I rritabil itate Arteriarum propria. Bonn. 1821, 4to. 634 Ch. H. Ehrmann, Structure des Arteres, leurs Proprietes, leurs Fonctions, etc. Strasb. 1822, 4to. 635 D. Belmas, sur la Structure des Arteres, etc. Strasb. 1822, 4 to. 636 C. Mayer, Disquisitio de Arteriarum Regeneratione. Bonn. 1823, 4to. 637 Rapp, liber die Wundernetze, in Meckels Archiv. 1827. 638 J. Miiller, Entdeckung der bei der Erektion des mannl. Gliedes wirksamen Arterien bei dem Menschen und den Thieren, in Miillers Archiv. 1835. 639 A. Barth, Diss. de Retibus Mirabilibus. Berol. 1837, 4to. 3. VEINS. 640 H. Fabricius ab Aquapendente, de Venarum Ostiolis, in Op. Omn. Anat. et Physiol. Prsef. est J. Bohnius. Lips. 1687. Prsef. est B. S. Albinus. Lugd. Bat. 1737, fol. 641 H. Meibomius, de Valvulis Vasorum, in Haller, Disput. vol. ii. 642 J. E. Hebenstreit, de Venis Communicantibus, in Haller, Disp. vol. ii. 643 J. G. Janke, de Ratione Venas Corp. Hum. angustiores ostendendi, vol. ii., in Sandifort, Thesaurus Disserta- tionum, Programmat. aliorumque Opusc. Select. Roterd. 1768-78, 3 tom. 4to. 644 H. Marx, Diatribe Anat.-Phys. de Structura et Vita Venarum. Carol. 1819, 8vo. 645 C. G. Jaeckel, Diss. de Absorptione Venosa. Berol. 1819, 8vo. 378 GENERAL VASCULAR SYSTEM. 646 C. F. Hemperich, Diss. de Absorptione et Secretione Venosa, Vratisl. 1822, 8vo. 647 F. Ribes, in Revue Medic. 1825, Juillet. 648 A. H. L. Westrumb, physiolog. Untersuchungen iiber die Einsaugungskraft der Venen. Hann. 1825, 8vo. 649 H. Ratbke, uber die friiheste Form und die Bildung des Venensystems in den Lungen beim Schafe, in Meckels Archiv. 1830. 650 , uber die Bildung der Pfortader und der Leber- venen der Saugethiere, in Meckels Archiv. 1830. 651 G. Breschet, anat.-physiologische Untersuch. liber einige neu entdeckte Theile des Venensystems. Erste Ab- theilung, von ben Blutaderkanalen der schwammigen Substanz der Schadelknochen insbesondre, in Acta Nova Acad. C. L. vol. xiii. part 1. 652 C. Mayer, iiber die Klappen in den Lungenvenen, in Tiede- mann und Treviranus Untersuch. etc. Bd. 3. 653 F. Rosenthal, de Intimis Cerebri Venis seu de Venee Magnae Galeni Ramis (s. 1. et a.). 654 J. H. F. Gunther, Untersuch. und Erfahrungen im Gebiete der Anat., Physiol, und Thierarzneikunde. Erste Liefe- rung. Hann. 1837, 8vo. Venenplexus des Pferdepenis. Ableitungsvenen und Compression derselben, beziiglich der Erektion. 655 H. Rathke, liber den Bau und die Entwicklung des Venen- systems der Wirbelthiere, im dritten Bericht iiber das naturwissenschaftliche Seminar bei der Universitat zu Konigsberg. Konigsb. 1838, 4to. 4. CAPILLARY VESSELS. 656 R. Vieussens, Novum Vasorum Corp. Hum. Systema. Amst. '1705, 8vo. 657 J. G. Janke, de Ratione Venas C. H. angust. etc. vol. ii. 658 J. N. Lieberkiihn, Diss. de Fabrica et Actione Villorum Intestinorum Tenuium Hominis. Amst. 1760, 4to. 659 H. van der Bosch, theoretische u. prakt. Bemerk. iiber das Muskelvermogen der Haargefasschen. Munster u. Osnabr. 1786, 8vo. 660 A. F. Hecker, iiber die Verrichtung der kleinsten Schlaga- dern u. ^iniger aus einem Gewebe der feinsten Gefasse bestehenden Eingeweide. Frft. 1790, 8vo. 661 J. G. Haase, de Fine Arteriarum cum Venis Anastomosi. Lips. 1 792, 4to. GENERAL VASCULAR SYSTEM. 379 662 B. N. G. Schreger, in Fragm. Anat. et Phys., fasc. i. Lips. 1791, 4to. 663 G. Prochaska, in Disqoisitio Anat. -Physiol. Organismi C. H. Vien. 1812, 4to. 664 K. Burdach, in den russisehen Sammlungen fur Natur- wissenschaft und Heilkunst. Bd. 2, 1817. 665 S. Th. Sommerring, in den Denkschriften der Miinchner Akad. der Wissensch. 1818-20. 666 J. Bleuland, leones Anat. Physiol, fasc. i. ii. Traj. ad Rh. 1827, 4to. 667 Schriften liber den Kreislauf von Haller, Spallanzani, Pro- chaska, Hastings, Oestereicher, Wedemeyer. 668 J. Dollinger, iiber die Vertheilung der feinsten Blutgefasse, in Meckels deutsch. Archiv. Bd. 6. De Vasis Sanguiniis queeVillis Intestinorum insunt. Monach. 1828, 4to. 669 E. Burdach, Berichte von der k. anat. Anstalt zu Konigs- berg. Achter Bericht rait Bemerk. iiber die ernahrenden Gefasse der Puls- u. Blutadern. Konigsb. 1835, 8vo. 670 Berres, Beobachtungen iiber die peripherischen Gefassver- zweigungen. Wien, 1832, 8vo. 5. LYMPHATIC VESSELS. 671 O. Rudbeck, Nova Exercitatio Anat. exhibens Ductus He- patis Aquosus et Vasa Glandularum Serosa. Aros. 1653, 4to. De Sero ejusque Vasis, in Haller, Disp. vol. vii. 672 Th. Bartholini, Opuscula Nova Anat. de Lacteis Thoracis et Lymphaticis Vasis. Hafnise et Francof. 1670, 8vo. 673 F. Ruysch, Op. Omnia. Amst. 1737, 3 vol. 4to. 674 A. Monro I. de Venis Lymphaticis Valvulosis et de earum imprimis Origine. Edinb. 1770, 8vo. 675 J. F. Meckel (sen.), Dissert. Epistolaris de Vasis Lympha- ticis Glandulisque Conglobatis ad A. Haller. 1760, 8vo. Ejusd. Nova Experimenta et Observat. de Finibus Ve- narum ac Vasorum Lymphaticorum. Berol. 1772, 8vo. 676 W. Hewson, Experimental Inquiries into the Properties of the Blood, Part II. Lond. 1774, 8vo. 677 J. G. Haase, de Motu Chyli et Lymphae Glandulisque Conglobatis. Lips. 1778, 4to. 678 W. Hewson, vom Blute, seinen Eigenschaften und einigen Veranderungen desselben in Krankheiten. Nebst einem Anhang betreffend die Entdeckung der lymphatischen Gefasse in Vogeln, Fischen und Amphibien. Niirnberg. 1780, 8 vo. 380 GENERAL VASCULAR SYSTEM. 679 P. Ch. F. Werner et Ch. G. Feller, Vasorum Lacteorum et Lymphaticorum Anat. Phys. Descriptio. Fasc. I. Lips. 1784, 4 to. 680 W. Cruikshank, the Anatomy of the Absorbing Vessels of the Human Body. Lond. 1786, 4to. ; 2d edit. 1791. Deutsch von Ch. F. Ludwig. Leipz. 1789, 4to. Neuere Beitrage, 1794, 4to. 681 B. N. G. Schreger, Beitrage zur Cultur der Saugaderlehre. Bd. 1. Leipz. 1793, 8vo. 682 P. Mascagni, Prodromo d’un Opera sul Sistemo de’ Vasi Linfatici. Siena, 1784, 4to. Vasorum Lymphaticorum Corp. H. Historia et Iconographia. Senis, 1787, fob DeUtsch mit Anmerk. und Zusatzen von C. F. Ludwig. Leipz. 1789, 4to. Vasorum Lymphat. Hist. S. totius Pars prima denuo edita, tom. i. Senis, 1795, 8vo. Deutsch, Leipz. 1799, 2 Tide. 8vo. 683 J. Ch. F. Isenflamm, de Absorptione Sana. Erl. 1791, 8vo. 684 G. J. Wollff, arzneikundige Abhandl. iiber den Nutzen der Wasser- oder Lymphengefasse. Aus dem Holland, von L. L. Finke. Lingen. 1795, 8vo. 685 B. Fohmann, Anatom. Untersueh. iiber die Verbindung der Saugadern mit den Venen. Heidelb. 1821, 8vo. 686 R. Lippi, Illustrationi Fisiologiche e Pathol, del Sistema Linfatico-chilifera, etc. Firenze, 1825, 4to. Vide Archives Gen. de Med. 1829, Aoht, Nov. 687 L. Gmelin, Versuche iiber die Wege auf welchen Sub- stanzen aus dem Magen und Darmkanal ins Blut gelangen, etc. 1826, 8vo. 688 V. Fohmann, das Saugadersystem der Wirbelthiere. Erstes Heft, Saugadersystem der Fische. Heidelb. 1827, fol. 689 J. C. Ogilvie, on the Interior Structure and Economy of the Conglobate Glands, in Lond. Med. and Phys. Journal, 1827. 690 J. F. Meckel (jun.) S. Th. Scemmerringio gratulatur. Lips. 1828, fob 691 A. Meckel, scheinbarer Uebergang einer Saugader in eine Vene, in Meckels Archiv. 1828. 692 V. Fohmann, iiber die Saugadern im Fruchtkuchen und Nabelstrang des Menschen, in Tiedemanns und Tre- viranus Untersueh. etc. Bd. 4. 693 J. Miiller, iiber die Existenz von vier getrennten, regel- massig pulsirenden Herzen, welche mit dem lympha- tischen System in Verbindung stehen, bei einigen Amphibien, in Mullers Archiv. 1834. GLANDULAR SYSTEM. 381 694 Panizza, liber die Lyraphherzen der Amphibien, in Mullers Archiv. 1834. 694* G. Valentin, liber die Anordnung der Muskelfasern in dem hintern Lymphherzen des Python. Repertorium, 1837, S. 294. 695 S. Lane, Art. Lymphatic System, Cyclop. Anat. and Phys. 695* J. Abernethy, on the Mesenteric Glands of the Whale, Phil, Trans. 1796, vol. lxxxvi. XXVI. GLANDULAR SYSTEM. 696 Th. Wharton, Adenographia. London, 1656, 8vo. and in Manget, Bibl. Anat. t. ii. 697 M. Malpighi, de Viscerum Structura, in Op. Omn. Lond. 1686. 698 A. Nuck, Adenographia. L. Bat. 1691, 8vo. and in Manget, Bibl. t. ii. 699 G. Mylius, de Glandulis, in Haller, Disp. vol. ii. 700 L. Ideister, de Vera Glandulae Appellatione. Altd. 1718, 4to. 701 J. Ch. Wolfen, H. Boerhaave and Fr. Ruysch, in F. Ruyschi Op. Omn. 702 C. G. Ludwig, de Glandularum Differentia. Lips. 1740, 4to. 703 A. L. de Hugo, de Glandulis in Genere et Speciatim de Thymo. Goett. 1746, 4to. 704 Th. de Bordeu, Recherches Anat. sur la Position des Glandes et sur leurs Actions. Paris, 1751, 8vo. 705 A. Schumlansky, de Structura Renum. Argent. 1788. 706 G. A. Haase, de Glandulis Cowperi Mucosis Comment. Lips. 1803, 4to. 707 G. A. Haase, de Glandularum Definitione. Lips. 1804, 4to. 708 Sommerring und Reisseisen, iiber die Struktur, Verrichtung und den Gebrauch der Lungen (gekronte Preischrift). Berl. 1 808, 8vo. 709 E. H. Weber, Beobacht. liber die Struktur einiger einfachen und conglomerirten Driisen und ihre Entvvicklung, in Meckels Archiv. fur Anat. und Physiol. 1827. 710 J. Muller, de Glandularum Secernentium Structura Pe- nitiori earumque Prima Formatione. Lips. 1830, fol. English by Solly. Lond. 1839, 8vo. 382 GLANDULAR SYSTEM. 711 F. F. Maercker, Diss. de Pancreate. Berol. 1830, 8vo. 712 C. A. Wollmiiller, Dissert, de Thymi Glandules Structura atque Functione. Berol. 1830, 8vo. 713 J. Muller, mikrometrische Messungen der Acini und sekretflihrenden Kanale der Drlisen im injicirten und embrvonischen Zustande, in Meckels Archiv. 1830. 714 C. Dziatzco, Diss. de Mammarum Structura. Berol. 1830, 8vo. 715 Klein, Diss. de Sinu Cutaneo Ungulorum Ovis et Caprae. Berol. 1830, 8vo. 716 F. L. A. Kelp, Diss. de Systemate Salivali. Berol. 1832, 8vo. 717 J. Muller, liber die Struktur der eigenthiimlichen Korper- chen in der Milz einiger pflanzenfressenden Saugethiere, in Mullers Archiv. 1834. 718 M. Nagel, Dissert, de Renum Succenturiatorum in Ani- malibus Structura penitiori. Berol. 1834, 4to. 719 L. Boehm, de Glandularum Intestinalium Structura pe- nitiori. Berol. 1835, 4to. 720 F. A. Wuerst, Diss. de Glandula Thyreoidea. Berol. 1836, 8vo. 721 J. Vogel, Prodromus Disquisitionis Sputorum in variis Morbis excreatorum. Erlang. 1838, 8vo. 722 Nagel, liber die Struktur der Nebennieren, in Miillers Archiv. 1836. 723 Fischer, de Puris Indole ejusque a Pituita discernendi Methodis. Dorp. 1836, 8vo. 724 A. Lereboullet, Anatomie Comparee de l’Appareil Re- spiratoire dans les Animaux Vertebres. Paris, 1838, 4to. 724*Dujardin et Verger, Recherches Anat. et Microscopiques sur le Foie des Mammifbres. Paris, 1838, 8vo. 725 G. Gulliver, on the Thymus and the Lymphatic Glands, Figures of the Corpuscles of the Liver and Spleen. Appendix to Gerber’s Anatomy. 725* E. Wilson, Art. Liver, in Cyclop. Anat. and Phys. 726 Bonnet, Traite CompletTheorique et Pratique des Maladies du Foie. 2e edition, Paris, 1841. 726* F. Kiernan, on the Anatomy and Physiology of the Liver, in Philos. Trans. 1833. CUTANEOUS SYSTEM. 383 XXVII. CUTANEOUS SYSTEM. 1. IN GENERAL. Ill A. Bonn, de Continuationibus Membranarum, L. B. 1763, 4to. In Sandifort, Thesaur. Diss. vol. ii. 728 H. A. Wrisberg, de Membranarum ac Involucrorum Corp. Hum. Continuationibus, in Comment. Gcett. 1786, 4to. 729 X. Bichat, Traite des Membranes. Paris, 1827. Reils Archiv fur die Physiol. Bd. 5. 730 J. B. Wilbrand, das Hautsystem in alien seinen Verzwei- gungen. Giessen, 1813, 8vo. 731 M. H. Hebreard, sur l’Analogie qui existe entre le Sys- teme Muqueux et le Dermoi'de. Mem. de la Societe d’Emulation, vol. viii. 2. MUCOUS MEMBRANES. 732 C. Billard, de la Membrane Gastro-intestinale dans 1’Etat Sain et dans 1’Etat d ’Inflammation. Paris, 1825, 8vo. 733 A. N. Gendrin, Hist. Anat. des Inflammations. Paris, 1826, 2 vol. 8vo. Deutsch von J. Radius. Leipz. 1828, 8 vo. 734 Rousseau, des Differens Aspects que presente la Mem- brane Gastro-intestinale, in Archives Generates de Me- dicine, t. vi. 735 A. de Brandt, Nonnulla de Anatome Membran. Muco- sarum. Berol. 1835, 8vo. 736 A. Th. Aepli, Diss.de Membrana Tympani. Gynop. 1837, 8vo. 737 Th. L. W. BischofF, iiber den Bau der Magenschleimhaut, in Mullers Archiv. 1838. 738 A. Wasmann, Diss. de Digestione Nonnulla. Berol. 1839. 738* S. Pappenheim, zur Kenntniss der Verdauung im gesunden und kranken Zustande. Breslau, 1839, 8vo. 739 Sprott Boyd, on the Mucous Membrane of the Stomach, Edinb. Med. and Surg. Journ. vol. xlvi. 739* T. Hodgkin, Lectures on the Mucous and Serous Mem- branes, 2 vol. 8vo. Lond. 1840-41. 3. SKIN. 740 Th. Bartholinus, de Integumentis Corp. Hum. Hafniee, 1655, 8vo. 38 4 CUTANEOUS SYSTEM. 741 M. Malpighi, de Externo Tactus Organo, in Op. Omn. Lond. 1686, fol. 742 A. Kaauw Boerhaave, Perspiratio dicta Hippocrati per Universum Corpus Anatomice Illustrata. L. B. 1738, 8 vo. 743 F. de Riet, Diss. de Organo Tactus. L. B. 1743, 4to. in Haller, Disp. t. iii. 744 J. Fantoni, Diss. Anat. VII. Taur. 1745, 8vo. 745 C. J. Hintze, Examen Anat. Papillarum Cutis Tactui in- serventium. L. Bat. 1747. In Haller, Disp. tom. vii. 746 C. F. Wolff, de Cute, etc., in Nova Acta Acad. Petropol. vol. vii. 1 793. 747 L. F. A. Keeler, Diss. de Odore per Cutem spirante. Gcett. 1794, 8vo. 748 W. Cruikshank, Experiments on the Insensible Perspiration. Lond. 1779 and 1795, 8vo. Deutsch von Michaelis. Leipz. 1798, 8vo. 749 G. A. Gaultier, Recherches Anatomiques sur le Systeme Cutane de FHomme. Paris, 1811, 4to. 750 G. Prochaska, Disquisitio Organismi Corp. H. Vien. 1812, 4to. 751 J. F. Schroter, das menschl. Gefiihl oder Organ des Getastes (Abbild.) Leipz. 1814, fol. 752 H. Dutrochet, Observat. sur la Structure de la Peau, in Journal CompRm. du Dictionn. des Sciences Medic, vol. v. 1820. 753 J. Purkinje, Comm, de Examine Physiol. Organi Visus et Systematis Cutanei. Vratisl. 1823, 8vo. 754 B. W. Seiler, von den Integumenten, in Pierer und Choulant’s med. Realworterbuch. Leipz. u. Altenb. 1826-29, 8 Bde. 8vo. 755 Wendt, de Epidermide Humana. Vratisl. 1833, 4to. Burkhardt, Schreiben der Baseler Gesellschaft. Heft 1. 756 H. Eichhorn, iiber die Aussonderungen durch die Haut und iiber die Wege durch welche sie geschehen, in Weckels Archiv. 1826. 757 H. Eichhorn, iiber die Anat. u Physiol, der aussern Haut. In Meckels Archiv. 1827. 758 E. H. Weber, Beobachtungen fiber die Oberhaut, die Hautbalge und ihre Vergrosserung in Krebsgeschwiilsten u. iiber die Haare des Menschen. Meckels Archiv. 1827. THE OVUM. 38.5 759 G. Breschet et Roussel de Vauz&me, Nouv. Recherehes sur la Structure de la Peau. Paris, 1835, 8vo. 760 Gurlt, vergleich. Untersuch. iiber die Haut des Menschen und der Haussaugethiere, besonders in Beziehung auf die Absonderungsorgane des Hauttalges und des Schweisses, in Mullers Archiv. 1835. 761 A. A. Berthold, einige Versucbe iiber die Aufsaugungs- thatigkeit (Inhalation) der Haut, in Mullers Archiv. 1838. 762 J. Hellwig, Diss. de Cute Hum. Marb. 1838, 8vo. 763 Madden, on Cutaneous Absorption. Edinb. 8vo. 763* R. Willis, Illustrations of Cutaneous Disease, a series of Delineations of the Affections of the Skin, in their more interesting and frequent Forms ; with a Practical Sum- mary of their Symptoms, Diagnosis, and Treatment, including appropriate Formulas. 96 plates and text, fol. Lond. 1841. XXVIII. THE OVUM, ITS ORGANISATION, DEVELOPEMENT, &c. 1. TI1E OVUM, ITS PRIMARY ORGANISATION. 764 Breschet et Raspail, Anat. Microscopique des Flocons du Chorion de l’CEuf Hurnain, in Repert. Gen. d’Anat. et de Physiol. Path. 1828. 765 E. Weber, Diss. Anat. Uteri et Ovariorum Puellse septimo a Conceptione die defunctae. Hal. 1830, 8vo. 766 S. Bock, Diss. de Membrana Decidua Hunteri. Bonnae, 1831. 767 A. Bernhardt, Symbola ad Ovi Mammalium Historiam ante Prsegnationem. Diss. Vratisl. 1834, 4to. 768 R. Wagner, einige Bemerk. und Fragen iiber das Keim- blaschen, in Mullers Archiv. 1835. 768* Wh. Jones, on the Ova of Man and Mammiferous Ani- mals, &c. Paper read at Royal Society, 1835. 769 F. J. F. Meyen, Diss. de Primis Vitae Phoenomenis in Fluidis Formativis et de Circulatione Sanguinis in Parenchymate. Berol. 1836, 4to. 770 G. Valentin, iiber den Inhalt des Keimblaschens, in Miillers Archiv. 1836. C C 386 EMBRYO. 771 C. G. Carus, Auffindung des ersten Ei- oder Dotter- blaschens in sehr friiher Lebensperiode des weiblichen Korpers und daraus abgeleitete Darstellung der Noth- wendigkeit ausser der bekannten, noch eigene, bisher in der Physiologie ganzlich nnbeachtet gebliebene Lebens- perioden lm Verlaufe menschlicher Entwicklung anzuer- kennen, in Mullers Archiv. 1837. 772 G. Valentin, iiber die Entwicklung der Follikel in dem Eierstocke der Saugetheiere, in Mullers Archiv. 1838. 773 M. W. Plagge, liber das Ei der Saugethiere vor der Befruchtung. 774 Flourens, Vorlesungen iiber Befruchtung und Eibildung. Uebersetzt unter Redaktion von Behrend. Berlin, 1838, 8 vo. 775 M. Barry, Researches in Embryology. First Series: Lond. 1839, 4to. Philos, Trans. 1 838, part 2. Second Series : ibid. 1840. Third Series: ibid. 1841. 2. DEVELOPEMENT OF THE EMBRYO. 776 J. Hedwig, de Fibrse Vegetabilis et Animalis Ortu. Lips. 1790, 4to. 777 E. H. Weber, Beitrag zur Entwicklungsgeschichte des menschl. Embryo, in Meckels Archiv. 1827. 778 C. Girou, Essai sur la Generation, Precede de Considera- tions Physiologiques sur la Vie et sur l’Organisation des Animaux, in Repert. Gen. d’Anat. et de Physiol. Path. 1828. 779 J. F. Meckel, Beitrag zur Entwicklungsgeschichte der Lungen, in Meckels Archiv. 1829. 780 J. Miiller, Zergliederung menschl. Embryonen aus friiherer Zeit der Entwicklung, in Meckels Archiv. 1830. 781 J. Miiller, de Ovo Humano atque Embryone Observ. Anat. Bonn. 1830, 4to. 782 R. Wagner, iiber die hinfallige Haut, ihren Bau und ihre Entstehung, nebst Untersuch. iiber die Veranderung, welche die innere Flache der Gebarmutter in den ersten Monaten der Schwangerfchaft erleidet, in Meckels Archiv. 1830. 783 G. F. O. Reich, Diss. de Membrana Pupillari. Berol. 1833, 4 to. 784 G. Valentin, Handbuch der Entwicklungsgesch. des Men- schen, mit vergleich. Riicksicht der Entwicklung der Saugethiere u. Vogel. Berl. 1835, 8vo. SECUNDARY FORMATIONS. 387 785 R. Wagner, Beitrage zur Gesch. der Zeugung u. Entwick- lung (aus den Abhandl. der math.-physik. Classe d. k. bair. Akad. d. Wissensch.). 786 R. Wagner, Prodromus Hist. Generationis Hominis atque Anim. Lips. 1836, fol. 787 Flourens, Cours sur la Generation, l’Ovologie et l’Embry- ologie. Par. 1836, 4to. 788 R. Wagner, die Genesis der Saamenthierchen, in Mullers Archiv. 1836. 789 O. G. Girgensohn, Bildungsgeschichte des Riickenmark- systems mit Benutzung der allg. Bildungsgescb. Riga u. Leipz. 1837. 790 Coste, Embryologie Comparee. Paris, 1837, 4to. Em- bryogenie Comparee. Paris, 1837, 8vo. 791 H. Rathke, liber die Entstehung der Glandula Pituitaria, in Miillers Archiv. 1838. 792 De Mirbel et Spach, Notes pour servir a l’Histoire de l’Embryologie Vegetale (Extrait des Comptes-Rendus des Seances de l’Academie des Sciences du 18 Mars, 1839), 4to. 793 Th. Schwann, mikroscop. Untersuch. liber die Ueberein- stimmung in der Struktur und dem Wachsthum der Thiere u. Pfianzen. Berl. 1839, 8vo. 794 R. Wagner, Handbuch der Physiologie, 8vo. Pt. 1, Ele- ments of Physiology, in English, by R. Willis ; On Generation and Developement. Lond. 1841, 8vo. 3. SECUNDARY ORGANISATIONS. 795 Breschet et Raspail, Anat. Microscopique des Flocons de Chorion de l’CEuf Humain, in Repert. Gen. 1828. 796 R. Wagner, liber die hinfallige Haut, ihren Bau u. ihre Entwicklung, nebst Untersuchungen iiber die Veran- derung, vvelche die innere Flache der Geb'armutter in den esten Monaten der Schvvangersehaft erleidet, in Meckels Archiv. 1830. 797 S. Bock, Diss. de Membrana Decidua Hunteri. Bonnse, 1831, 4to. 798 H. Nasse, mikroscop. Beobachtungen liber die Bestand- theile des Blutes und der sich zur Faserhaut gestaltenden Fllissigkeit, in Untersuch. zur Physiol, u. Pathol, von Fr. u. H. Nasse. Erstes Heft. Bonn. 1835, 8vo. 388 PARASITES. 799 L. Gueterbock, Diss. de Pure et Granulatione. Berol. 1837, 4to. (Praemio Aureo Ornat.). 800 H. Wood, Diss. de Puris Natura atque Formatione. Berol. 1837, 4to. 801 T. Wharton Jones, on the Origin of the Chorion, &c. Philos. Trans. 1837. XXIX. PARASITES. 1 . ENTOZOA. 802 M. E. Bloch, Abhandlung von der Erzeugung der Einge- weidewlirmer. Berl. 1782, 4to. 803 C. A. Rudolphi, Entozoorum sive Vermium Intestinalium Hist. Naturalis, tom. ii. Amst. 1809, 8vo. 804 Ejusd. Entozoorum Synopsis, etc. Berol. 1819, 8vo. 805 Bremser, liber lebende Wlirmer im lebenden Menschen. Wien, 1819, 4to. Trad, en Franqais, 1 vol. 8vo. and atlas, 4to. Paris, 1837. 805* Bremser, leones Halmenthum System. Rudolphi illust. fol. 18 plates. Viennae, 1823. 806 A. H. L. Westrumb, de Helminthibus Acanthocephalis Comment. Historico-anatomica. Hannov. 1821, fol. 807 Jules Cloquet, ,Anat. des Vers. Intestinaux, Ascaride Lom- brico'ide et Echinorhynque Geant. Memoire Couronne par l’Acad. Royale des Sciences pour l’Ann6e 1818. Paris, 1824, 4to. 808 E. Mehlis, Observationes Anatomicae de Distomate Hepatico et Lanceolato. Goett. 1825, fol. 809 B. Meyer, Diss. de Entozoorum Natura et Indole. Berol. 1832, 8vo. 810 Raspail, Naturgesch. des Insektes der Kratze, _aus dem Franz, mit Anmerk. von G. K. Leipz. 1835. 81 0* Hertwig, iiber Kr'atz- und Raudemilben, in Gurlt und Hertwig, Mag. fur Thierheilkunde, 1835. Heft 2. 811 E. M. Heyland, Diss. de Acaro Scabiei Hum. Berol. 1836, 4 to. 811*G. Gulliver, on the Structure of the Cyst-Worm, Med. Chir. Trans, vol. 24. 812 Werner, Vermium intestinalium praesertim Taeniae Hu- manae. 2 vol. 8 vo. fig. Leipsig, 1782-88. SUPPLEMENT. 389 812*Goeze, J. A. E. Versuch einer Naturgeschrichte der Ein- gerweidewiirmer thierischer Korper. Mit. 44, Kupf. and Af. 4to. Leipzig, 1787. 2. INFUSORIA. 813 C. G. Ehrenberg, die Infusionsthierchen als vollkommene Organismen. Ein Blick in das tiefere Leben der Natur. Leipz. 1838, fol. XXX. MEANS TO AID. 814 D. Moser, Anleit. zum Gebrauche des Mikroscops. Berl. 1839, 8vo. Mullers Archiv, Valentins Repertorium, etc. 815 R. Wagner, Grundriss der Encyklop'adie u. Methodologie der raedicin. Wissenschaften. Erlangen, 1838, 8vo. 815*W. B. Carpenter, Art. Microscope, in Cyclopaedia of Anatomy and Physiology. SUPPLEMENT TO TIIE ELEMENTARY WORKS ON PHYSIOLOGY. 816 Bourdon, Principes de Physiologie Comparee. 8vo. Paris, 1830. 816* Arnold, Physiol, des Menschen. Bd. 2, 1839. C. G. Carus, System der Physiologie. Dresd. u. Leipz. 1839, 8vo. 817 R. Wagner, leones Physiol. Fasc. I. II. Lips. 1839. Fasc. III. ib. 1841. Plates Illustrative of General Anatomy, Physiology, and Developement ; incorporated in Dr. Willis’s Translation of the Author’s Elements of Physiology. Part I. On Generation and Developement. Lond. 1841, 8vo. 817* W. B. Carpenter, General and Comparative Physiology. Lond. 8vo. 1841. 818 Fischer, de Puris Indole ejusque a Pituita Discernendi Methodis. Dorp. 1836, 8vo. 819 Danneil, de Suppuratione. Beroi. 1838, 8vo. 390 SUPPLEMENT. 820 G. Valentin, liber die Spermatozoen des Baren, in Acta Acad. C. L. C. Nat. Cur. vol. xix. p. 1, 1838. 821 J. F. Rosenthal, Dissert, de Formatione Granulosa in Renis aliisque Partibus Organismi Animalis. Vratisl. 1838, 8vo. TO THE EVOLUTION OF THE EMBRYO. 822 D. F. Eschricht, de Organis quse Respirationi et Nutritioni Foetus Mammalium inserviunt. Hafn. 1837, 4to. 823 Jos. Hodgson, on the Arteries and Veins, 8vo. Bond. 1815. CORRECTIONS. PAGE 34 Note, line 30, for object-glass, read object-plate. 35 Note, line 4, for found clots of fibrine too compact, read found that clots of fibrine were too compact. 36 Note, line 12, after discs, erase the comma, and add G. G. to the note. 58 Note, line 1 ,for its substance, read the substance of the gland. 134 Note, line 9, for shrewmouse, read shrew (S orejc tetragonurus). — — line 23, fur vesicles, read larger vesicles. 162 Note,_/er ciliee, read cilia. 179 Note I, line 7, for is, read has been. 190 Note, line 6, for parencbyme, read parenchyma. 200 Note, line 2, for were, read are. 233 Note, line 7, after absent, insert or not visible without the aid of an acid. 270 Note, line 3, erase the words that is. APPENDIX. 6 Note, line 2, for Typhus, read Typus. 15 Line 31, for Plate 18, read Plate 28. 20 Line 10, after nucleoli, insert or nuclei. EXPLANATION OF PLATES. 59 Line 4, for employed, read applied, and erase designate. pig. 263 For 800, read 380. 276 For blood-smooth, read smooth blood. 280 Line 6, after the word and, insert this appearance. 294 The corpuscles are magnified 800 diameters. itaniiitrit dmntifir HSnrk*, PUBLISHED BY HIPPOLYTE BAILLIERE, 219, REGENT STREET, LONDON, AIVD 169, FUETOIV STREET, KEW YORK, U.S. J. BAILLIERE, LIBRAIRE, RUE HAUTEFEU1LLE, PARIS. BAILLY BAILLIERE, LIBRAIRE, CALLE DEL PRINCIPE, MADRID. Mr. B. having lately opened a house in New York for the sale of Scientific Works , begs respectfully to state that he will now be enabled to supply any American Books on Science and General Literature, immediately after Publication, at Reasonable Prices. H. B. continues to receive a weekly parcel from France, containing the newest Works on Science and General Literature, which he supplies at the rate of One Shilling per Franc on the advertised Price in Paris. 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