QJ CM4s 1853 ■^ ■t SYLLABUS fif THE LECTURES PHYSIOLOGY AND HISTOLOGY; INCLUDING TH OUTLINES OF COMPAKATIVE ANATOMY, DELIVEKBD AT THE Inihrsitg si Virginia, B Y J. L. CABELL, M.D. I. V I I PMSTED FOR THE USE OP THE MEMBERS OF THE CLASS. UNIVERSITY OF VIRGINIA:—McKENNIE & SON. 185 3. ttk*.C U.4 sf /£<■ &' ■' <■ -*> i /A-; fi-e n * \ (in'i-Hs, t rfn i fMtK 7 ■"■ / h e, ERRATA. The attthor*s Want of practice in correcting proof caused him to overlook many errors of the press, in the first impression, and the distance between his residence and the city where these pages were printed precluded the possibility of a second correction. Accord- ingly the existing errors are very numerous, but to avoid making the list too long, ho omits such of them as the intelligent reader will readily correct for himself, as where a singlejetter is omitted, or where the singular number is Used instead of the plural, and vice versa., of both classes of which there are many examples. Page 6, line 11, for "blood, plasma" read "blood-plasma.'* 15, line 6, for "secretive" read " secreted." 16, line 14, for " tenacity" read " tonicity." 17,line 37, for " Chloride''read "Hydro-chlorate.'* 19, XII class, for " membrane. fiArOus" read "membrano-fibrous." 22, line 18, for"contractible" read "contractile." 22, last line, for " Physical" read "Physiological." V 49, line 7, for " Amphineurta" read " Amphinecsta. > . „ » 49, line 10, for AxghtiT read "^AxolotLJ' \ _\ X .Vv Vt * .^;^¥ for^y^i*reai"^?hical.'»V.N \s% % S w s. • 59, line 327 for "same" read Several." v \ * * \4."^ ^-« V » S S«W \ * V '■ ■"V-":. ■ v v>* s \ ^V • «v V • x- V, » , N V v % v * X \\ \# l^\ V: vv\ V ' ■■" \V V v% v xv% nn • V %*v*' ^* *v^ *v v v V «• v « v * s,* v* V v % ,n\ N W \>*o >*v ♦ S# KJ V ^ V^ v, v \v V 4 ~v " / Cm 4c I &^'p/*j?m *^ ^*7 '^^ *• 4^/ ^> jy PREFACE. A Syllabus of Lectures, consisting of the mere heads of the topics which are to be fully expounded in the oral discourses of the teacher, can have no value except to the students who listen to these discourses. It can, therefore, scarcely be necessary that I should disclaim all intention of publishing these pages, which are printed for the exclusive use of the members of my class. It had long been my custom to write upon a blackboard the heads of the topics discussed in each lecture, which served the two-fold purpose of lessening the difficulty of taking notes, and of facili- tating references to the text-books and other authorities that might be occasionally quoted. The task of copying these notes from a blackboard, which from the arrangement of the room was unavoid- ably placed in an unfavorable position as regards the light, was found to be so onerous, that I have felt myself constrained, by the urgent solicitation of many members of the class, to have them printed. In view of the single use for which they are designed, I have not regarded it as necessary or important to mark off the subjects by any formal arrangement of Sections and Chapters, contenting myself with merely numbering the paragraphs consecutively from the beginning to the end. For the same reason I have deemed it unnecessary to prepare a "Table of Contents." Those "who attend iv PREFACE. the lectures will readily understand the principle governing the arrangement of the subjects, and will therefore easily know where tofind the appropriate place for each topic. It will be observed, that Histology and the Outlines of Com- parative Anatomy are taught with direct reference to their appli- cations to Human Physiology, and, indeed, as a necessary part of a complete exposition of the latter subject. Accordingly, the consideration of these topics is introduced into the body of the work, after a preliminary exposition of certain generalities on the nature and objects of Physiological Science, and before the dis- cussion of the Special Physiology of the several functions. In several instances I have deemed it expedient to abandon, for one or more paragraphs, the form and style of a syllabus, and to substitute a more continuous statement of matter in hand, espe- cially when this embraced abstract generalities not fully expounded in the text-books, my experience as a teacher having satisfied me that most youthful minds find much difficulty in apprehending such generalities on a single hearing, or with only a compendious statement of them in the form of a syllabus for revisal. But in the main I have conformed to the principle of a syllabus, and have presented only short summaries of the subjects which are amplified and illustrated in the lectures. The almost exclusive reference to Carpenter's Elements of Physiology, and Kirkes & Paget's Human Physiology, is explained by the fact that these works are both used as text-books. SYLLABUS OF LECTURES OF COMPAEATIVE ANATOMY AND PHYSIOLOGY. OF PHYSICAL SCIENCE IN GENERAL. 1. Definition of Science in its most enlarged sense, as com- prising all attainable knowledge of natural bodies and phenomena, when such knowledge is " orderly and methodically arranged." Distinction between mental and physical science. 2. Two-fold subdivision of physical science into natural his- tory and natural philosophy. Natural history views objects as they exist in space, and simply observes and narrates phenomena as they are directly addressed to the senses. It should, indeed, arrange and classify objects according to their relations of form, colour, structure, and other similar qualities, but it does not specu- late upon their active phenomena viewed as causes and effects, which is the appropriate province of natural philosophy. Illustrative ex- amples : zoology, botany, and anatomy, are branches of natural history, while mechanical philosophy, chemistry, and physiology, are branches of natural philosophy. 3. But inasmuch as the aim of natural history is to describe and classify objects, it may take cognizance of the actions and changes of bodies so far as they characterize the latter, provided it does not seek to explain such actions, but only adopts them as facts that may be of use in furnishing the basis of a natural classification. An acquaintance, to a certain extent, with natural history, must precede the study of natural philosophy, since we must collect, verify, and classify facts, before we can interpret or explain them. In natural history we do not go beyond the observation and clas- sification of phenomena. In philosophy we begin with natural history, (collection of facts,) and regarding phenomena as effects, aim to explain them by the discovery of causes and laws. Exposition of the special object and methods of the study of physiology. 4. Physiology.—That branch of natural philosophy which seeks to discover the laws under which the actions of living beings are performed. Animal physiology may be studied with reference exclusively to the actions of the human frame, (human physi- ology,) or with reference to the whole animal series, (comparative physiology.) Brief statement of the importance of the study of comparative animal and vegetable physiology. o syllabus, etc. 5. Two classes of facts embraced in the narrative division of physiology, namely, (1) the characters of the ORGANS or material instruments by which the actions of life are manifested, and (I) the functions or special operations of the several organs. The inves- tigation of the first of these two classes of facts is the special object of anatomy. Thus one branch of the physiological problem con- sists in seeking to establish the connexion between organs and their functions, and may be thus stated: an organ being given, to dis- cover its action or function, or conversely, a vital act^ being recog- nised, to discover the organ or organs concerned in its execution. Examples: 6. Evidence on which functions are assigned to given organs, (a) Evidence derived from direct observation, (b) From experiments'—sources of fallacy in deriving positive conclusions from experiments on living animals of a high grade. Nega- tive information from this source more reliable, (c) From pa- thological observation—why more reliable than that derived from the effects of sudden and artificial changes, (d) From compara- tive anatomy. The contemplation of the anatomical structure of a single species throws little light on the investigation of func- tions, except where these are purely mechanical, in which case we note the adaptation of the organ on mechanical principles for a special use. The comparison of extensively varied types of ani- mal forms, all executing substantially the same fundamental phe- nomena of life, enables us to ascertain what are the essential con- stituents of each organ, and what are the other essential conditions of its action. Comparative anatomy thus furnishes " so many kinds of experiments ready prepared by nature-" 7. After assigning to an organ its appropriate function, or after having traced an observed action to the organs concerned in its manifestation, it remains to explain or interpret it, which consti- tutes the second branch of the problem. Only legitimate sense in which a natural phenomenon can be said to be explained—elucida- tion of the conditions under which it is exhibited. Systematic arrangement of those conditions under the following heads— (a) Proximate cause, or that inherent property of matter to which the phenomenon in ^ question may be traced as an ultimate fact. Examples—The action of muscles in displacing parts, traced to a peculiar property inherent in muscular fibre, by virtue of which the fibre, under certain circumstances, becomes suddenly and ac- tively shortened. The ascent of the piston in a steam-engine, traced to the expansive power of steam, a property inherent in that material, and exhibited under certain circumstances. (b) Exciting causes, or stimuli—The power of contracting, which is inherent in muscular fibre, vet requires to be excited or stimulated as a condition of its manifestation. As the ao-encies which fulfil this office, may be said in a certain sense to cause or occasion the resulting action, they are indifferently termed ex- citing, occasional or determining causes, or STIMULI. SYLLABUS, ETC. 3 (c) Laws.— Apart from the foregoing, there are other conditions which indicate the mode and especially some limitation of the effects resulting from the assigned causes, and these are termed laws, as being expressions of the will of the Author of Nature. Ultimate properties identified by their laws. Thus, to prove that apparently diverse phenomena are really due to the same proximate cause, it must be shown that they are governed by the same laws. Ex- amples :— (d) Final causes. As in attempting to explain the construction and operation of a complicated machine, we have not only to in- dicate the use or function of each separate part, and to show how such action depends on the properties inherent in its material, but must also point out the connexion between the independent actions of the separate parts and the workings of the machine as a whole, so in the study of Physiology we must show how the operation of the separate organs contribute to the general welfare of the organism by subserving special uses subordinate to that common end, and such uses are termed final causes. The contemplation of final causes presents to the rightly constituted mind incontestable evidence of intelligent foresight and contriving skill, and hence forms the basis of the science of natural theology. Final causes not to be substituted for physical causes. The former indicate the bene- ficent designs of Providence, the latter disclose the instrumental methods employed, under certain determinate conditions or limi- tations, by Infinite Wisdom to work out these designs. 8. Method of arriving at positive results in the research for causes and laws. Observation does not directly and imme- diately indicate causes and laws, but supplies the data which the mind spontaneously and intuitively groups in appropriate order according to natural relations, so as to infer from this comparison general facts or laws. Such act of inference is the main element in the inductive process of thought, by which we discover the laws of nature. Illustration—Laws of human enactment made known by proclamation, oral or printed; laws of nature discovered only by observing facts, and from the uniformity of their sequence in the past, inferring a like uniformity in the future. Brief statement of some of the rules of procedure for facilitating the research by induction for the laws which govern complex phenomena, (a) Particular observations must be sufficiently numerous and extend- ed, to eliminate sources of error. Illustration, (b) In assigning causes we may often avoid error by inquiring whether a suggested cause be appropriate, that is, whether on the ground of analogy it be likely to have such a relation with the effects to be explained. The assigned cause must be a vera causa, (c) Again it must not only be a vera causa, but it must be adequate in degree. 9. Of the employment of the deductive process in the investiga- tion of general truths. Our inductions are often accompanied and aided by the deductive process, as when we make a provisional as- sumption, and having deduced the consequences involved in such Special Anatomy or Organography. 4 / syllabus, etc. ,7 /. assumption, proceed to compare them with the observed phenomena, so as to verify or refute the hypothesis, thus anticipating the slower process of simple induction. Used in this way, the process of de- duction may be made strictly subordinate to the most rigorous in- duction. But this logical artifice needs to be used with caution in the sciences that treat of vital phenomena, since in them the ma- thematics cannot be employed to verify or refute the assumption. general view of the chemical and structural composition of the human body. 10. The distinct subjects of inquiry in the two leading divisions of Human Anatomy, are exhibited in the following scheme, re- presenting the successive stages of the anatomical analysis of the fabric. (a) The body is resolved into a number ofs Organs of which the form, weight, co- lour, situation, local connexions and struc- ture are to be determined. (b) In investigating the structure of organs,) these are resolved into their constituent tissues, a limited number of which are combined in various ways, so as to form all the different organs of the body. (c) In taking note of the anatomical char-\ acters of the several tissues, we observe that they too are compound structures, and resolve them into a small number of STRUCTURAL ELEMENTS Or PRIMARY forms of organization, such as homo- geneous membrane, fibres, cells, nuclei and granules. (d) Thus far the analysis is exclusively ana- tomical, and the properties of the ma- ) terial concerned are unchanged. By a different method of analysis, as the re- Histology. suit of which the properties of tissues are wholly transformed, we reveal their chemical composition, exhibiting at the first stage certain proximate animal principles, such as albumen, fibrin, gelatine, fatty principles, &c, and by a further process reducing these to the ultimate elements of matter. / N B. Histology (a description of tissues) is not strictly sy- nonymous with general anatomy, which comprises, in addition to the anatomy of the simple tissues, all the generalities which may be predicated of classes of organs, such as bones, muscles, glands, &c. General Anatomy 77'// /" '■''iiyr / I44tt ? syllabus, etc. 5 / ^ 11. Definition of chemical or ultimate elements of matter, which by their various combinations make up all known material objects, such as gases, liquids, earths, stones, and the bodies of animals, and plants. Example : limestone may be separated into two proxi- mate ingredients, namely, a gaseous body, which is driven off by a high temperature, called carbonic acid, and a white caustic solid, known as quick lime ; but each of these ingredients is a compound, the former consisting of carbon and oxygen, and the latter of cal- cium and oxygen. These last named substances cannot be reduced any further, and are presumed to be elementary. 12. Sixty-one or two such elements, are found in the mineral kingdom, and only about seventeen ever enter into the composition of animal structures, namely, oxygen, hydrogen, nitrogen, carbon, sulphur, phosphorus, chlorine, potassium, sodium, calcium, magne- sium, iron, fluorine, and occasionally manganesium, silicon, alumi- nium and copper. The first four are named essential elements, the others incidental elements. 13. Proximate organic principles of determinate characters, are the products of chemical decomposition of organised structures, short of their ultimate analysis. Example: a substance known, as animal jelly or gelatine is separated from certain animal tissues by protracted boiling. It is, therefore, one of the constituents of animal flesh, but being itself a compound of carbon, oxygen, hy- drogen and nitrogen, it is termed a proximate principle. The various proximate principles entering into the composition of the human tissues may be classified either according to their chemical or their physiological relations. See Kirkes and Paget's Human Physiology, chapter I. for the chemical classification. An arrange- ment founded on physiological relations is thus stated by Carpen- ter (Human Physiology, Ed. 1853). (a) The Histogenetic substances destined to become part of the organised fabric by progressive metamorphosis. (b) The calorific substances, which are either introduced into the body as components of the food, or which are formed within it, by the metamorphosis of the histogenetic substances, or of the com- ponents of the tissues themselves. These substances are destined to undergo oxidation, and thereby to generate heat, and are all of the saccharine, or of the oleaginous class, or are derivable from them by very simple transformations. (c) The components of the actual living tissues. (d) The excrementitious substances which are formed within the body as the products of the disintegration, and retrograde meta- morphosis of its tissues, and which are on their way from these to the outlets of the excretory apparatus. They constitute a group of substances, which are intermediate in their chemical character between the foregoing and inorganic matter. For a detailed account of the sensible character and chemical re- actions of albumen, caseine, gelatine, chondrine and fibrine, and their relations to proteine, see Carpenter's Elements of Physi- SYLLABUS, ETC. ology § 167 to § 187 inclusive. Other organic proximate com- pounds will be noticed in connection with the description of the tissues in which they exist. B.—STRUCTURAL COMPOSITION OF THE HUMAN BODY. 14. The animal organism in its integrity as a living machine, consists of fluids and solids. The fluids divided into (a) forma- tive fluids, as lymph, chyle and blood and (b) secreted fluids, such as bile, saliva, urinekc, &c. The solids constitute the dif- ferent tissues. Both fluids and solids are composed of certain structural elements, which may be classified thus: (1) Liquid blastema, such as the fluid bloody -plasma. (2) Solid cytoblastema, as the intercellular ma- trix of cartilage, &c. (3) Primary membrane, forming walls of cells and of the finest blood-vessels. (a) Amorphous Elements, which show no trace of structure, being simple and" homogeneous. (b) Primary organic forms, which are so arranged as to constitute tissues of deter- minate structure, some of them being themselves com- posed of definitely arranged dissimilar parts. (4) Granules {Free, as in chyle, milk, or inclosed, as in pigment cells, or imbedded, as in bones and teeth. , Free nuclei, either floating in a liquid, as those of gas- tric juice, or loosely imbed- ded in solid substance, as in the vesicular matter of the brain and spinal marrow. Attached nuclei, either closely imbedded in homo- geneous substance, or fixed to the surface of fibres or membranes, or finally in- closed in cells. ' Free and either floating as those of lymph, chyle and blood, or loosely imbedded in solid or semisolid sub- stance, as those of the grey matter of the brain, epithe- lium cells, &c. Cells whose walls have coalesced while their cavi- ties remain distinct. Cells whose cavities have coalesced so as to form tu- bules. Fibre-cells, or cells trans- formed into solid fibres. Cells whose cavities are more or less obliterated by secondary endogenous de- posit. ^(1) Primary fibres, formed directly without cell-agency. See Human Physiology by Kirkes and Paget, Chap. II. (5) Nuclei or cyto- blasts, minute vesicles with walls of simple membrane and usually inclosing, besides a pel- lucid fluid, one or more minute granules of a peculiar appear- ance, called nucleoli. (6) Cells, which are vesicles of larger ave- rage size than nuclei. In their perfect condi- tion they generally con- tain each a nucleus and sometimes two nuclei. A cell thus consists of a nucleus inclosed to- gether with liquid con- , tents in a secondary^ vesicle having homo- geneous membranous cell-walls. syllabus, etc. 7 GENERAL ANATOMY OF THE HUMAN TISSUES. A. Simple Fibrous Tissues. 15. Anatomical characters of the white elementary fibre. Its occasional origin in the direct fibrillation of fibrinous plasma, inde- pendently of cell-agency—its occasional origin from transformed cells—its chemical composition and reactions—its uses. Car- penter's Elements, §188-9, §180-183, §193. 16. Anatomical characters of the yellow fibrous element—micro- scopic tests—chemical composition and reactions. lb. § 190-192. 17. General anatomy of the tissues and organs composed exclu- sively of the white fibrous element, and hence termed the white fibrous tissues. Distribution. Tendons of muscles. Most ligaments. Investing membranes of bones and many other organs. Conformation, funi- cular, fascicular, membraniform; naked eye characters, colour, polish, fibrous arrangement; microscopic characters, physical 'pro- perties, vital properties, chemical composition, uses. 18. General anatomy of the yellow fibrous tissues, found pure and unmixed in the ligamenta sub-flava, ligamentum-nuchse, vocal cords, and in a stratum of fibres constituting a part of the arterial tunics. Found inseparably mixed with the white fibrous element in areolar tissue, and with cartilage in the ear, nose, epiglottis, &c. For other characters, see Carpenter's Elements, loc. cit. 19. Areolar tissue formerly called cellular tissue. Definition; white fleecy body, composed of translucent and softish fibres, con- necting the skin with the subjacent organs and these with one another. Distribution; subcutaneous, sub-mucous, subserous, intermediate and investing, interstitial, parenchymal or interlobular, &c. Confor- mation ; arranged in masses whose outline is determined by the shape of the space they are to fill, and susceptible of being flattened into membranous fasciculi. Structure ; fibres and lamellae intersect- ing in various directions. Microscopic characters. Mixture of white and yellow elementary fibres; former predominating, latter of very variable dimensions, some being excessively minute, and wound spirally around the white band-like fibres. Other characters are such as would result from its composition as a mixture of the two fibrous elements. 20. Serous membranes, comprising also synovial membranes.— Definition. Distribution. Conformation, a membrane arranged in the form of a short sac, presenting a free surface, smooth and polished, and an adherent surface»with a subserous areolar tissue. Structure: next to the free surface a layer of tessellated epithelium cells, resting upon a basement primary membrane itself supported by an areolar derm very delicate, but condensed and nearly non- 8 syllabus, etc. vascular, the vessels not extending beyond the subserous lax areolar tissue; this last is generally lax and contains fat, but is sometimes dense and close. Physical and vital properties— Uses. Peculiarities of synovial membranes and of their relations with articular cartilages before and after birth. 21. Mucous membranes constituting the internal integument. Distribution; (a) alimentary tract and its glandular appendages. (b) Respiratory tract, (c) Lachrymal tract, (d) Genito-urinary tract, (e) System of glands and follicles opening on the skin. Conformation ; membranes with a free, and an attached surface of variable thickness—free surface more or less villous except in the more delicate specimens, which approximate to serous membranes ; attached surface areolar; body spongy; colour more or less reddish according to the different degrees of vascularity of different speci- mens ; redness uniform, ramiform, or punctiform. Structure: next to free surface there is a layer of epithelium cells which may be tessellated, cylindrical, or spheroidal. This layer rests on a base- ment membrane supported by an areolar derm, which is commonly thicker than that of serous membranes and is generally very vas- cular; arrangement of the vessels in the villi; arrangement of vessels around the mouths of follicles; nerves of mucous mem- brane. Physical and vital properties—uses. See Carpenter's Elements, § 199 to § 205 inclusive. (B.—BASEMENT OR PRIMARY MEMBRANE. 22. Definition—Three varieties: (1) simple amorphous mem- brane seemingly formed directly from the nutritive fluid, by a simple consolidation of a thin layer; (2) a membrane with minute granules imbedded in its substance, as if the blastema from which it was formed had included nuclear granules ; (3) a membrane with distinct spots arranged at equal or variable distances, and having a tendency to break up into portions of equal size, as if it had been formed by the coalescence of cells whose cavities had been ob- literated and their contents removed, but whose nuclei had con- tinued to perforin their peculiar functions. Distribution : on all the free surfaces of the body, beneath the epithelial or epidermic cells. Uses &c. See Carpenter's Elements, § 206 to § 209 inclusive Kj.—STRUCTURES COMPOSED IN PART OF SIMPLE ISOLATED CELLS. 23. Hhtory of an independent animal cell; its structure ; albu- minous cell-wall; contents variable, but generally include a nu- cleus which is itself vesicular and may contain a nucleolus. De- velopment, in one of two modes; (1) from pre-existing cells 'either by subdivision of parent cell, or by endogenous multiplication • SYLLABUS, ETC. 9 (2) by a new production of cells in an organizable plasma, which is then called cyto-blastema. Carpenter, loc. cit. § 210 to § 213" inclusive. \ 24. Formative fluids, chyle, lymph and blood. Definition ; (a) notice of the anatomical characters of the cells, which are common to all of these fluids and which are variously named, chyle corpuscles, lymph corpuscles, and white or colourless corpuscles of the blood; globular, with finely granulated surface, about 3^00 mchin diameter; the addition of water causes a delicate cell-wall to rise up from the granular nucleus with which it was previously in contact. Uses ; they are now commonly regarded as embryo blood disks, and are probably concerned in the assimilation of crude albumen into vitalized fibrine. (b) Red discoid cells of the blood, improperly called blood globules.—Form—Biconcave disks having a circular outline in man and the mammalia generally, except only the camel tribe, which have elliptical disks; as have also all the oviparous vertebrates. Average diameter in man ^Ve inch. Thickness, one-quarter the diameter. Tendency to run together in piles when drawn from the body. Effects of certain re-agents in altering their shape. When exposed to a liquid denser than serum, they give out a part of their fluid contents and become corrugated; if the liquid be less dense they absorb water and swell out into the form of biconvex lenses. Structure ; colourless cell-wall, tolerable thick and tough; no nucleus in the blood disks of mammals. Other vertebrata have a distinct granular nucleus, identical with that of their chyle cor- puscles, the colouring matter being superadded around the latter. Chemical composition, uses, vital properties, &c, to be noticed in connexion with the special physiology of the blood. 25. Epidermis or Cuticle. Definition; naked eye characters; physical properties. Microscopic structure. Next to the base- ment membrane we have a semifluid cytoblastema; then a stratum of nuclei or cytoblasts, then epidermic cells of primordial char- acters ; then flattened cells, and lastly mere scales, the result of the desiccation of cells. Uses; Carpenter, loc. cit. §224 to §228.- 26. Pigmentary body. Definition ; a group of cells sometimes mingled with epidermic cells as in the skin of Africans; sometimes forming a distinct body, as in the pigmentum nigrum of the eye, which cells secrete colouring matter instead of horn. Anatomical and chemical character of pigment granules. Development of pig- 'ment cells. Carpenter §§ 229 and 230. — 27. Epithelium. Definition. The epidermis of mucous and serous membranes, whose constituent cells are never so completely flattened as to destroy their organization. General characteristics, those of nucleolo-nucleated cells. Varieties. (1) Tessellated, found on all serous and synovial surfaces, and on the endangium of blood- vessels and lymphatics, and on the smaller ramifications of gland ducts, except in the very follicular ends. (2) Columnar or Cylin- drical, found on all mucous membranes, except where other varieties 10 'SYLLABUS, ETC. are specified. (3) Spheroidal, found on the urinary tract from mouth of bladder up to the smaller uriniferous tubes, where it is displaced by the tessellated, on the mammary ducts, and in the terminal fol- licles of most glands. (4) Scaly, which is rather a soft cuticle than a true epithelium, found on the mucous membrane of the mouth, pharynx and oesophagus, terminating at the cardiac orifice of the stomach in a. fringed border. Ciliated epithelium, is the name applied to any of the foregoing varieties when they are beset on their free side with Cilia (from " Cilium," an eyelash,) little hair-like vibratile processes from T¥fo o to 5-57 mch long? and im- measurably fine, found on the epithelium of respiratory tract, ven- tricles of the brain, and in the uterus and Fallopian tubes. Chemi- cal composition: Uses. All the vegetative functions executed through the instrumentality of cells either epithelial or strictly analogous to these in their origin, as chylosis, hsematosis, aeration of the blood, nutrition, secretion and generation. Carpenter, loc. cit. § 231 to § 247. D.—Tissues, composed in part of cells that are connected TOGETHER AS PERMANENT CONSTITUENTS. 28. Such cells are connected either by a general enveloping membrane, or by an intercellular cement, the sacculi containing cells of adipose tissue exemplifying the former, and the hyaline matrix of cartilage the latter. 29. Adipose tissue. The structure containing the animal fat. Distribution. Sub-cutaneous, except on eyelids, pinna, scrotum and penis. Intermuscular; between the fasciculi of many muscles, around certain organs, as the eye, kidneys, base of the heart, &c. sub-serous, but never sub-mucous; in the medullary cavities and cancelli of bones—never in the lungs or in the cavity of the cra- nium. Fatty principles, but not adipose tissue, found in chyle and blood, either mechanically suspended or chemically dissolved. Found, likewise, intimately united with other ingredients, in many solids, as muscular fibre, and especially nervous matter, which has two peculiar fats; also excreted by sebaceous follicles of the skin. Finally, is formed as a morbid product, indicating degeneration of normal tissues, as fatty liver, &c, &c. For structure and develop- ment of adipose tissue, and its relations with areolar tissue; for chemical characters of oleine, margarine and stearine, physical pro-' perties and uses of fat, see Carpenter, loc. cit., §257 to §203,-"" inclusive. 30. Simple, or cellular cartilage. Definition. The white gristle which incrusts the articular heads of bones, &c. Distribu- tion. (1) Articular or incrusting cartilage. (2) Framework of larynx, trachea, bronchi, &c. (3) The unossified segments of the skeleton. These three are ^permanent cartilages," although number (3) is closely related to (4.) Temporary cartilage, or car- syllabus, etc. 11 tilage of ossification. Form. Incrusting or articular cartilage of variable thickness, and thinning off at the edges, has a free, smooth surface, and another attached to the bone. Colour. Bluish- white, or pearly; translucent in thin slices. Structure. Appa- rently homogeneous to naked eye; non-articular varieties covered by perichondrium; articular, covered on free surface by synovial membrane, as proved before birth, by a layer of intervening vessels, which disappear after birth; these never have a perichondrium. Microscopic character. Nucleolo-nucleated cells, imbedded in an apparently homogeneous hyaline matrix, with which the cell walls coalesce; cells multiply by binary division; hence, often seen in groups. By a very high power Dr. Leidy resolved the apparently homogeneous matrix into an exceedingly close tuft of very fine fibres. Chemical characters, physical properties and uses, see Carpenter, loc. cit., § 264 to § 273, inclusive. —- 31. Fibro-cartilage. Definition. Cartilage, of which the pe- culiar cells are imbedded in a net-work of white or yellow fibrous tissue in place of the hyaline matrix. Distribution. (1) Yellow fibro-cartilage found in the external ear, nose, epiglottis, tarsal cartilage of eyelids, &c. (2) Interarticular disks. (3) Articular marginal cartilages for deepening sockets. (4) Connecting or interosseous cartilages. (5) Cartilages lining the bony grooves in which tendons of muscles glide. For other characters, see Car- penter, loc. cit., § 269. .___ 32. Bone. Two varieties of structure, the spongy or cancel- lated, and the compact or ivory. (1) Cancellated, how constructed; medullary membrane and oil. (2) Compact structure, very con- densed, system of Haversian canals, &c. Three classes of bone distinguished by their form. (1) Thick or irregular, a mass of cancellated structure, covered by a thin shell of compact matter. (2) Flat bones, having two tables of a compact bone and an inter- mediate cancellated structure, presenting certain peculiarities, and called diploe. (3) Long bones, consisting of a shaft and two arti- cular ends or epiphyses ; medullary canal in the shaft; medullary membrane and fat; arrangement of blood-vessels. Microscopic characters. Elementary bony lamellae, covered by delicate medul- lary membrane, whose vessels never enter the substance of the lamella. Osseous corpuscles or lacunas, with radiating canaliculi. Interlacunar matrix of close fibres, with calcareous granules im- bedded. Dimensions and other characters of lacunae and canali- culi in different classes of vertebrates. 33. Mode in which the two varieties of bony structure are built up of the elementary lamellae. (1) Spongy or cancellated struc- ture. Compound lamellae, formed of several layers of the elemen- tary forms in close union, and covered with a highly vascular medullary membrane intersect to form cancelli, which are filled with reddish oil. (2) Compact structure formed of fasciculi of ossicles, closely packed together and arranged around the medul- 12 SYLLABUS, ETC. lary canal. An ossicle, a cylindrical rod of bone, pierced longi- tudinally by the canal of Havers, from ^Vo to sh of an inch' or about gfa as an average. The bony walls of this canal formed of several concentric cylinders of elementary lamellae, fitting within each other with exceeding closeness, and each containing an im- mense number of lacunae and canaliculi. Arrangement of these "plasmatic tubes," with reference to the Haversian canal, the ex- terior of the ossicle, and the intervening substance. Very minute dimensions of the canaliculi. A few lamellae concentric with the medullary canal. Lateral communications between contiguous Haversian canals, so as to constitute a coarse net-work. Chemical composition, physical properties, uses, see Carpenter, § 288 to § 299r- 34. Development of bone. Three stages of osteo-genesis. (1) Gelatinous stage, consisting of primordial cells in a semi-fluid blastema. (2) Cartilaginous, representing the different temporary cartilages. A few flat bones are fibro-membranous in place of being cartilaginous. (3) Ossific stage, which may succeed either the membranous or the cartilaginous condition. (a) Intra-membranous ossification. The flat bones forming the roof of the cranium, prior to ossification, exhibit "only a mem- branous layer, made up of white fibres and granular corpuscles, with a soft, amorphous or faintly granular uniting matter." The corpuscles are true cells, with an envelope and granular contents, most being two or three times larger than blood corpuscles. The fibres are calcified by impregnation with calcareous granules—a very vascular spot, (punctum ossific at ionis,) near the centre of the surface, indicating the point at which the process commences. Blood vessels, at first superficial, soon become inclosed by pro- gressive deposits around them, and thus determine the formation of Haversian canals. The progressive extension of the ossific deposit in radiating spjcula, with oblique connections, making a loose net-work, that afterwards becomes compact. The original granular corpuscles, it is probable, shoot out tortuous lines, and those organs resisting the deposit of calcareous matter, form the lacunas and their radiating canaliculi. (b) Intra-cartilaginous ossification. Arrangement of the carti- lage cells near the punctum ossificationis. Penetration of blood- vessels to such point. First appearance of provisional bone (with- out lacunse, $c.,) in form of a net-work, occupying the spaces be- tween the columnar groups of cells. Subsequent enlargement of the areolae of this temporary bone, from which the cartilage cells seem to disappear, and are replaced by a blastema, derived from the neighbouring vessels, and giving rise, by development, to a fibrous membrane and a new set of cells. These new structures then undergo ossification, in concentric layers, within the spaces bounded by the coarse temporary bone first formed. Formation of lacunae and canaliculi from the cells of this ossifying fibrous membrane. Formation of Haversian canals. Bone, first spongy SYLLABUS, ETC. 13 and very vascular, may become very compact and almost non- vascular. Relation of the temporary cartilage to the permanent elements of bone. Growth and regeneration of bone. See Car- penter, § 300 to § 309, inclusive. ---" 35. Teeth. General conformation ; crown or body, neck, and root or fangs, alveolus, alveolo-dental periosteum. Varieties of forms. Incisors, canine, bicuspids, molars. Dental formula of man. Structure. Cavity of the pulp, canal extending through the fangs, dentine, enamel, crusta petrosa or cement. Microsco- pic characters. (1) Of the pulp. (2) Of dentine, which consists of ' microscopic tubules, opening by their large end into the cavity of the pulp, and radiating in lines perpendicular to the walls of this cavity towards the periphery of the tooth. The diameter of these tubular rods, at their large end, 4$Vo? Avith a bore of twott inch; at the peripheral end, which exhibits numerous branches, they are immeasurably fine. Intertubular substance faintly granular. (3) Enamel. Prismatic, solid fibres, so closely packed that there is no intervening material; prisms four or six sided, adhering by one end to dentine, and free by the other; -5-^ inch in diameter. (4) Cementum has characters of true bone. Chemical characters of dentine and enamel, Carpenter, § 310 to § 319. — 36. Development of teeth. Embracing, (1) an account of the formation of a tooth as a whole; (2) the formation of each of its structural constituents ; and (8) the successive evolution of the different teeth in two sets—namely, the deciduous and the per- manent set. (a) Development of the individual teeth as distinct and entire organs. (1) Papillary stage. Papillae, consisting of a mass of cells, inclosed by structureless membrane, and lodged in the pri- mitive dental groove. Commences in seventh, and completed in tenth week of embryonic life, to be immediately succeeded by (2) the follicular stage, which is completed at the thirteenth week. (3) Saccular stage. Follicles closed by opercula, and become sacs. Structure of dental sac. External fibro-cellular layer; and internal highly vascular layer, lined with epithelium. Cavity of reserve be- tween the operculum and the point at which the lips of the sac approach to cohere together. Development of future permanent teeth in these cavities, which are thus offsets from the sacs of the deciduous teeth. (4) Eruptive stage. Shortly before the closure of the follicles, the papillae begin to assume forms more character- istic of teeth, and soon exhibit the exact shape of the crown of the coming teeth; henceforward called pulps. After a time, vary- ing with the different teeth, the outer layer of the pulp becomes _ transformed and calcified into dentine, the process commencing on the cusps as an exceedingly thin shell, looking like an excretion moulded on the cusps. Successive enlargement in surface and thickness, the pulp becoming proportionally smaller in breadth^ and thickness, but being elongated towards the bottom of the 14 SYLLABUS, ETC. cavity. The incorporation of calcareous matter with this elon- gated fang, causes the tooth to be lifted towards the gum, which opposes less resistance than the bony surface at the bottom of the alveolus, until ultimately the crown of the tooth is said to cut its way through the sac and the gum, those tissues giving way, how- ever, by progressive absorption and not by laceration. (b) Formation of each of the structural constituents of a tooth. (1) The pulp. See Carpenter, § 310. (2) Dentine. lb., § 313 and §314. (3) Enamel and cementum. lb., § 320. (c) Successive evolution of the different teeth in two sets. (1) De- ciduous set, twenty in number. Dental formula. Incisors, § -§; canine, y T; molars, f -§. Order of eruption. Middle incisors, lateral incisors, first molars, canine, second molars. Eruption commences at about seventh month after birth, and completed from eighteenth to thirty-sixth month. Order in which they are shed to be re- placed by permanent teeth. The process of shedding is usually preceded by the eruption of the first permanent molar, behind the last deciduous molar, in the seventh year. Then the deciduous teeth drop in the following order, to be replaced in each case by a permanent tooth: Middle incisors, lateral incisors; first molar to be followed by first bicuspid of permanent set; second molar to be followed by second bicuspid ; canine, which is the last of the deci- duous set to fall out, occurring in the thirteenth year. Then appear second permanent molars, and finally, from sixteenth to thirtieth year, the third molars or wisdom teeth. Development of permanent teeth in cavities of reserve, between the closed mouths of the sacs of deciduous teeth and their oper- cula. The permanent molars, however, lying beyond the range of deciduous teeth, form an exception. The first permanent molar, appearing before the shedding of any deciduous tooth, is developed at the back part of the primitive dental groove. Second molar de- veloped in a cavity of reserve, an offshoot from the sac of the first, and the third from the second. Shifting of the position of the second, and especially of the third permanent molar, in the progress of the growth of the deciduous teeth and of the jaw bone. Possible consequences of the confinement of the wisdom teeth in the ramus of the jaw. Carpenter, § 321 to § 325, inclusive. 37. Hair.—In many respects analogous to teeth. Hair follicle— hair bulb and pulp. Cortical substance of a fibrous, horny texture. Medullary substance of a more distinctly cellular character. Mi- croscopic characters of human hair—cortical layer, "a thin trans- parent horny film, composed of flattened cells or scales, arranged in an imbricated manner, their edges forming delicate lines upon the surface of the hair—within this a cylinder of fibrous texture, forming the principal part of the shaft, and only in the centre is there a distinctly cellular structure." Pigmentary matter between the fibres and in the cells, or sometimes equally diffused. Develop- ment of the several structures. Carpenter, §§ 329, 330. -___- • syllabus, etc. 15 E. Tissues composed of cells coalesced into tubes. 38. Dentine would be placed in this category by some histolo- gists, but others deny the cellular origin of the dentinal tubules. Two classes of tubes having such origin, (1) those without any sec- ondary deposit and serving as channels for the circulation of the nutritive juices, or else for conveying off the secretive fluids ;,£<.£,-,-*, and (2) those with secondary deposit, such deposit being organized elements executing vital acts, as muscular and nervous fibres. Only the minute capillary vessels which are intermediate be- tween the arteries and veins, and the smaller portion of glandular ducts, have their origin in the coalescence of cells laid end to end, the larger vascular and glandular tubes being formed of several layers of fibrous tissue, lined in the case of blood-vessels with a peculiar kind of serous membrane called endangium, and in the case of gland ducts with mucous membrane. 39. Arteries—Definition. General form of a limited portion of an artery—of the whole arterial tree—of the trunk divested of its branches. Relation of the collective areas of the trunk and all its branches at any given distance from the heart, with those nearer to or farther from it. Structure. (1) External fibro-areolar tunic, pene- trated by the nutrient vasa vasorum. (2) Middle tunic formed ofyel- loiv elastic and pale unstriped muscular fibres, most of which are circular but some longitudinal. They are arranged in layers, of which as many as forty have been counted in the aorta. The elastic fibres predominate in large arteries—the pale muscular in the small. (3) In- ternal tunic, or arterial endangium, consists of a layer of tessella- ted epithelium cells, resting on a peculiar, brittle, perforated or fenestrated membrane, which curls up when torn in shreds. The artery thus constructed is inclosed, with or without satellite veins, in a fibro-areolar sheath, to which it is united by a somewhat lax areolar tissue. Appearances of a living artery, color, pulsations. Patulous state of a dead artery emptied of its blood, provided it be of medium size or over. Anatomical relations—Satellite veins and nerves enclosed in a common sheath, arterial anastomoses. Physical properties.—Extensible, dilatable and elastic, owing these qualities mainly to the characters of the middle coat. Internal coat very brittle under the pressure of a sharp edge, such as a nar- row thread. Vital endowments—power of tonic contractions. 40. Veins.—Definition—general form and distribution. Veins are similar to arteries in these respects, but are larger or more nu- merous, and less apt to retain their cylindrical form when emptied. Anastomoses more frequent. Structure, analogous to that of arte- ries; (1) external coat thin but tough; (2) middle coat has few if any yellow elastic fibres, the pale muscular fibres which also are sparse, being mixed with white fibrous tissue. Internal coat more 16 syllabus, etc. seroid, and less fragile than the arterial endangium, and is thrown into semi-lunar folds strengthened by included fibro-areolar tissue, so as to constitute valves which yield to the column of blood moving towards the heart, but prevents its reflux towards the capillaries. Sensible appearances of a living vein; bluish cylinder when filled with blood; no pulsations ; easily compressible, collapsed when emptied. Anatomical relations.—Generally each artery lies be- tween two satellite veins, except the larger arterial trunks which are accompanied by a single vein each. Sub cutaneous or super- ficial veins without accompanying arteries. Veins and arteries run apart from each other in the cranial cavity, vertebral canal, and some bones; vasa vasorum penetrate to the inner tunic. Physical properties—flexible, extensible and dilatable: less elastic and less brittle than arteries. Vital endowments: veins have less tenacity than arteries, but a superior plastic force. A-n-v rV >'■ 41. Capillaries.—Definition. Test of their distinctive charac- ter: calibre not diminished by division, nor increased by union. Small arteries recognized in observations on the circulation of a living animal, by noting that the corpuscles move from trunks in diver- gent branches of a smaller size. In veins the currents converge from small tubes into larger ones. Form of capillary system in different tissues, a net-work of anastomosing tubes, the meshes being arranged conformably to the disposition of the component structural elements of the tissue or organ. Examples. Average diameter of a capillary blood-vessel joW inch, but some are much smaller and others greatly larger. Automatic variations of calibre in the same vessels in a living animal. Structure—Capillaries under ^iirs inch have a simple homogeneous membrane, resulting from the coalescence of the walls of a number of cells. On each side they gradually assume additional elements, so as to pass into arteriesand veins respectively. Around articular cartilages and in erectile tissues the minute arteries pour their blood into dilated pouches whence the veins arise. The same arrangement exists in the placental portion of the uterine walls in pregnancy. Develop- ment of blood-vessels, from nucleated cells sending out ray-like pro- longations which coalesce and form a network of channels, &c, &c. ^ 42. Muscular Tissues, Definition; the tissues endowed 'with vital contractility, and which, thereby, become the active instru- ments of the automatic movements of animals, are termed mus- cular. Two varieties ; (a) those muscles which are subservient to the functions peculiar to animals, are characterized by a striped appearance of their ultimate fibres : (b) most of the muscles con- cerned in effecting those movements which are subservient to the functions of organic life, are characterized by pale, unstriped 43. Striated variety of muscular tissue. Distribution; all the voluntary muscles, those of respiration and expression, the heart upper part of the gullet, and the muscles of the urethra. General form and structure. Body or venter, head, origin and insertion syllabus, etc. 17 both of which are often tendinous.. Fasciculi of red, soft fibres, mostly parallel to each other, though some may intersect as in the heart; areolar or fibrous sheath, interfascicular areolar matter, blood vessels and nerves and their relations to the proper muscular elements. Microscopic characters. Primitive or ultimate fibre striated with alternate light and dark spaces in a transverse direction; structure of fibre tubular, with delicate homogeneous wall, called myolemma or sarcolemma, with closely packed fibrillse deposited in the tube, and from being originally cylindrical, becom- ing prismatic by mutual pressure in a fasciculus. Structure of a fibril; a chain of quadrangular bodies separated by pellucid spaces, in the middle of which a faint line can be perceived. The pellucid space also extends around the sides of the dark bodies. These appearances probably due to quadrangular cells, whose walls are pellucid, and whose cavities are filled with a highly refractive material. Explanation of the cross striae. Lateral adhesion of the cells sometimes greater than longitudinal cohesion, and then the contents of a tubule separate by transverse cleavage into disks; average diameter of a tubule 3^> inch in male, and 4rb- in female. Average diameter of fibril To£oo inch. Carpenter, § 332 to § 336 inclusive. ---- 44. Unstriped variety of muscular tissue. Distribution; found in all the muscles of organic life, except the heart and upper part of the gullet. For its peculiar characters see Carpen- ter, §§ 337 and 338, from which it will be seen that the striated---- fibre is the perfect condition of the tissue, the contractile cells of Kolliker and the pale unstriped nodose fibre representing early stages of its development. The contractile cells with long staff- like nuclei are often found unmixed in the smaller arteries, veins, and lymphatics, &c, &c. 45. Chemical characters of muscular tissue. The albumen and gelatine found in muscles probably belong exclusively to their nerves, vessels and interfascicular areolar tissue. Fibrine, the chief solid ingredient, is probably the sole solid organic ingredient in pure muscular fibre. The juice of muscle contains kreatine, kreatinine, inosinic acid, lactic acid, and certain salts, especially //'; those of potash, (chloride and phosphate.) Physical properties of muscular tissue when relaxed ; when vitally contracted. Vital endowments: plastic force, tonicity and rythmical contractility. general anatomy of the nervous system. 46. Definition.—Varieties of nervous structure, (1) ganglionic or vesicular; (2) fibrous or white substance : fundamental office of each. 47. Fibrous or white nervous substance. Distribution; forms the trunk and branches of all nerves and also the white matter of the brain and spinal cord, where it comes into relation 2 18 syllabus, etc. with the ganglionic or vesicular substance. Structure of nerves. Neurilemma—fasciculi—ultimate nerve fibres, of which there are two kinds; (a) tubular or nerves of animal life, diameter jVoo to j^j inch in nerves, but very minute, (rdro-cr inch) in some parts of the brain; external homogeneous envelope, white matter of Schwann, and axis cylinder; more delicate tubes apt to become vari- cose under the least inequality of pressure, (b) Gelatinous, or nerves of organic life: flattened, soft and homogeneous, resembling un- striped muscular fibres ; nucleated nodosities ; diameter between BoVo and 40V0 inch. See Carpenter, § 373 to § 375 inclusive. —~- 48. Ganglionic, vesicular, or cineritious substance.— Distribution: found on the surface of brain and cerebellum, and in circumscribed masses in the substance of these organs; as a continuous longitudinal mass in the centre of each half of the spinal cord ; in the knotty enlargements called ganglia found on the posterior roots of spinal nerves, and on some other nerves ; and finally at the peripheral expansion of some of the nerves of special sense. Naked eye characters as found (1) in brain and spinal cord; (2) in ganglionic knots on nerves. Microscopic characters. Ganglion vesicles of various shape and dimensions, disseminated through a granular matrix, and lying somewhat loosely in the midst of a minute plexus of blood-vessels. Carpenter, § 378 to -~ § 380. 49. Anatomical relations of the two varieties of nerve structure, (a) In the brain and spinal cord. (1) Continuity of fibres with ray like prolongations of the cells. (2) cells included in a follicular dilatation of nerve tube. (3) Fibres merely passing among and around, possibly adhering to, but having no organic continuity with the ganglion cells. (b) Relations of the peripheral ends of nerves with the structural elements of the tissue to which they are distributed, (1) in muscles : loops of nerve tubes around ultimate muscular fibres, or else a net work of the ultimate nerve tubes. (2) Of sensory nerves. In some cases, as in the retina, we find an expansion of vesicular matter, which by analogy is presumed to exist for all sensory nerves. (c) Relation of nerve fibres within the trunk and branches of nerves. Mere juxtaposition and no anastomosis. Nervous plexuses, their structure and uses. Carpenter, §§ 376 and 377. 50. Chemical characters of nervous substance. Waste—devel- opment—regeneration-^wtaZ properties, $c. lb. § 384 to § 390.__ 51. CLASSIFICATION OF THE HUMAN TISSUES FOUN- DED ON THE CHARACTERS OF THEIR STRUCTURAL ELEMENTS. I. Molecules or Granules. (1) Molecular base of chyle. (2) Granular blastema. (3) Granular contents of pigmentary and other cells. syllabus, etc. 19 II. Nuclei, or Cytoblasts. III. Simple, homogeneous membrane. IV. Simple fibres. V. Nucleated cells, free and floating. (4) The assimilating corpuscles of the " so-called vascular glands," such as the thymus, thyroid, spleen, &c. (5) The free nuclei in the gastric glands and juice. (6) Nucleated blastema, as on the sur- face of open wounds, &c. (7) Mammalian blood disk(?) accord- J ing to T. W. Jones. (8) Basement or primary membrane. (9) White fibrous tissue, as in tendons and ligaments. (10) Yellow fibrous tissue, as in the vocal cords, &c. (11) Areolar tissue, and the derms formed of it. (12) The corpuscles of chyle and lymph, and the white cells of blood. (13) Red blood-disks of oviparous ver- tebrates. (14) Absorbent cells imbedded in the substance of the intestinal villi, and engaged in chylosis. (15) Adipose cells. (16) Vesicular nervous structure. (17) Epithelium and cuticle. VI. Cells imbedded in a vascular net- work, with or without a soft granu- lar blastema. VII. Independent cells, slightly held together by a mucous cement, and so arranged as to form membranous expansions. VIII. Cells with cavities distinct, but ' with walls coalesced by means of intercellular matter. IX. Sclerous elements, in which both THE CELL WALLS AND THE INTERCELLULAR MATRIX HAVE BEEN HARDENED BY HORNY OR BONY DEPOSIT. X. Cells transformed into tubes with- 1 (24) Capillary blood and lymph ves- out secondary deposit. / sels. XI. Cells converted into tubes with "t (25) Muscular tissue. secondary deposit./i.i^u^^,^,., v, <«, J (26) Fibrous nervous structure. XII. Compound membran# — Fibrous " structures, consisting of basement membrane and a layer of cells, with or without a derm beneath the mem- brane. (18) Cartilage. (19) Fibro-cartilage. (20) Hair and nails, consolidated with horny matter. (21) Bone. 22) Dentine, 23) Ename LilOiULCi . e: ] tine, >■ mel, J with calcareous mat- ter. (27) Serous "] (a) Common serous m. membrane, j- (b) Synovial " " embracing, J (c) Endangium. (28) Mucous membranes. OUTLINES OF COMPARATIVE ANATOMY. ON THE VALUE OF COMPARATIVE ANATOMY, AS SUPPLYING MOST OF THE DATA ON WHICH THE INDUCTIONS OF PHYSIOLOGY ARE BASED. 52. Complexity of the mechanism of man and other animals high in the zoological scale. Mutual dependence of the organs and cor- relation of functions. Action of each organ thus dependent on two sets of conditions; (1) those which immediately and directly in- fluence it, and which may, therefore, be called essential; and (2) 20 syllabus, etc. those which primarily concern other organs, and only exert an in- direct and reflected influence upon a given organ, for the reason that there must be a harmony of action throughout the system ; these last conditions, though important, or even necessary are not essential in the sense employed, and may be called conco- mitant or incidental conditions. Examples: essential conditions of muscular contraction, contrasted with certain conditions which are incidental to the peculiar organization of man, in respect to the relation between muscular action and the functions of the heart and lungs. Simple observation of the vital acts in one species will not enable us to discriminate between the essential and inci- dental conditions, since both are necessary to the^ continuance of the acts, and, for the same reason, artificial experiments are pre- cluded. But nature presents us with experiments already pre- pared, by exhibiting a chain of beings of continually decreasing complexity of organization, until we arrive at some in which any- given function is executed in its simplest and most essential condi- tions. Ascending from this point, we notice the successive super- additions to each organ or apparatus of organs, and comparing these with the habits, sphere of life, and other peculiarities of the beings which exhibit them, we learn, by an easy induction, the uses or functions of the numerous superadditions which we find in most of the human organs, as compared with the simplest and most elementary state of the same organs in the lowest animals. ON THE CHARACTERISTICS OF ORGANIZED STRUCTURES IN GENERAL. 53. Division of natural bodies into animals, vegetables, and minerals, the last comprising all bodies, whether solid, liquid, or gaseous, that do not belong to one or the other kingdom of living beings. Peculiarities of animals and vegetables, as contrasted with mineral matter. (1). Peculiar structure, called organization. An organism, a union of dissimilar organs, i. e. parts differing in structure and office, and yet all working towards some common end. So each organ is composed of different tissues, and each tissue of certain structural elements, most of which exhibit, under the microscope, a peculiar structure, and all of which are unlike mine- ral particles. Minerals are mere aggregations of similar particles, each having all the properties of all the rest. See Carpenter, loc. cit. §§ 4, 5, and 6, for apparent exceptions, &c. (2). Form.'" Organic forms contrasted with crystals, both as to appearance and as to the forces under which they are respectively developed. (3). Size. (4) Intimate structure and consistence. Carpenter, § 2 to-—' § 10 inclusive. (5) Chemical composition. See Kirke and Paget's Human Physiology, chap. I. Notice especially the following "~" points, (a) Small number of elements found in the organized kingdoms, not more than 16 or 17 out of the 62 found in the mineral-kingdom, and the relatively large number (4, 5, or even SYLLABUS, ETC. 21 more) in most of the organic proximate compounds, (b) Their complex mode of union in forming these compounds, contrasted with the binary mode of union of the elements in inorganic com- pounds, (c) The large number of organic compounds formed out of a few ultimate elements, (d) Proneness to spontaneous decom- position dependent in part upon the complexity of composition, and favoured by the presence of nitrogen and water. (6) The posses- sion of peculiar forces, which only exist while the organization is perfect. Mutilation of the organism not only arrests the action of the machine as a, whole, but destroys the capacity for action in each part; whereas, in inorganic machines, the properties of the material are unaffected by the disturbance of its action from mutilation or other influences. Hence, our notion of organization implies not merely a mutual adaptation of dissimilar parts, but also the pos- session by each part of peculiar forces, which only exist while the entire organism is perfect. ON THE DISTINCTIONS BETWEEN ANIMALS AND VEGETABLES. 54. Amplification and explanation of the aphorism of Linnaeus, that " minerals grow; plants grow and live; animals grow, live, and feel." Thus the "vital powers of a plant are directed solely to the performance of the formative operations," and whatever movements it may exhibit, have reference to the same end, and originate in physico-vital forces that are entirely independent of consciousness. An animal possessing these same powers has also others that " are subservient to the operations of the conscious mind, so that consciousness and spontaneity are involved in many of its movements which thus originate in psychical causes." (Carpenter.) But signs of consciousness in lower animals are often equivocal. Adaptive movements following a received stimulation, do not re- quire that the stimulus be felt, or that the movement be voluntary. Brief notice of physico-reflex acts. Besides there are certain organisms (Protozoa) admitted to be destitute of consciousness, and yet having more points of analogy in their structure and com- position with animals than with plants, resembling the embryonic or transitional forms of higher animals. Hence, other grounds of distinction than the possession of consciousness are needed. (1) Chemical characters. Though vegetables have a proteinaceous compound entering into the composition of the primordial utricle, and form and store up other proteine compounds, yet they have their tissues mostly composed of cellulose, a ternary compound. All true animal tissues, on the other hand, are composed of azo- tized compounds, having four or more elements. (2) Mode of ali- mentation. Animals feed only on matter already organized. Plants alone have the power of generating organic compounds, by the union of their elements obtained from ammonia, carbonic acid, and water. Difficulty occasionally experienced in applying this as a 22 SYLLABUS, ETC. test. (3) The antagonistic influences of animals and plant on the purity of the atmosphere. Vegetables thus abstract from the at- mosphere carbonic acid and ammonia, the chief sources of its im- purity, and convert them into organized compounds, which are stored up in its tissues. These are taken in by animals, to be assimi- lated to their own structure; and, after fulfilling a temporary use as the instruments of vital actions, are, in those very acts, again disintegrated and returned to the atmosphere as carbonic acid, ammonia, and water, the identical impurities which the plant had originally removed, and which will be again removed by other plants. Thus, under the reciprocal actions of plants and animals, the " chemical and physiological balance of organic nature" is constantly maintained. (4) Structure, (a) Most animals require a digestive sac, in which to receive and melt down the organic compounds on which alone they feed. But this is an adaptive rather than an essential character, and may be wanting in low ani- mal organisms, (b) Nervo-muscular apparatus. Some plants appear to possess a conjrajptible tissue, which may be considered as the lowest form of a muscular apparatus; but where there are both nerves and contractile tissue, or even nerves alone, the organism can only be animal. SUMMARY OF THE DISTINCTIONS BETWEEN ANIMALS AND VEGETABLES. AN ANIMAL, is an apparatus of combusti . n ; possesses the faculty of locomotion; 1 carbon, ~\ Existing in sugar, hydrogen, I starch, fat, albu- ammonium; J men, fibrine, &c. Exhales carbonic acid, water, oxide of ammonium, nitrogen; Consumes oxygen, neutral azotized matters, fatty matters, amylaceous matters, sugars, gums ; Produces heat, electricity; Restores its elements to the air or to the earth; Transforms organized into mineral matters. A VEGETABLE, is an apparatus of Reduction ; is fixed; Reduces carbon, hydrogen. ammonium; Fixes carbonic acid, water, oxyde of ammonium, nitrogen; Produces oxygen, neutral azotized matters, fatty matters, amylaceous matters, sugars, gums; Absorbs heat, Abstracts electricity; Derives its elements from the air or the earth ; Transforms mineral into organic matter (Dumas and Boussaingault's Chemical and Physical Balance of Organic Nature.) A SYLLABUS, ETC. 23 GENERAL VIEW OF THE ORtaA&IC KINGDOM. 55. Primary division of the animal kingdom into sub-kingdoms or departments, founded on the arrangement of their nervous system, which is an index of the general powers of animals, and consequently of the totality of their organization. Four dif- ferent types or patterns, according to which the nervous system is arranged in the different animals possessing such an apparatus. A large group of organisms reckoned animal, and yet altogether destitute of nervous material. Hence, five sub-kingdoms, viz.:— vertebrata, articulata, mollusca, radiata, and protozoa. 56. Vertebrata, Spini-Cerebrata, or Myelencephala [myalos "spinal marrow," and encephalon, "the brain.") Ani- mals having the vertebrate type of nervous system, that is, with a cerebro-spinal axis, consisting of coalesced ganglia inclosed in a jointed vertebral column of bone or cartilage, and lying on the dorsal side of the nutritive apparatus- Brain, the anterior ex- panded part of this axis, consisting of the ganglia of special sense and certain superadded parts largely developed in the higher spe- cies. Generally five senses. Bilateral symmetry. Jaws always open in the line of the axis of the body. Red-blood disks. Never more than two pairs of special locomotive members. Ex. Fishes, reptiles, birds, beasts, &c 57. Articulata or Homogangliata, with the Homogangliate type of nervous system; that is, a double ventral cord with ganglia at short intervals, generally a pair (right and left), coalesced on the middle line for each of the jointed annular segments of which the trunk is composed, and communicating anteriorly by nerves surrounding the gullet, with a pair of supraoesophageal ganglia usually coalesced into a bilobed mass connected with the nerves of special sensation and therefore regarded as a brain. In several of the higher articulates, the ganglia of several contiguous rings may coalesce longitudinally, and the resulting mass be drawn into one of the segments, as in certain insects, spiders, &c. But even though such coalescence were complete, the sub-abdominal posi- tion of the nervous axis would distinguish it from the spinal axis of vertebrates, which always lies on the dorsal side of the abdo- men. Bilateral symmetry of body. Jaws open laterally. Blood generally colourless, and when coloured, as in the annelida, it is due to the liquor sanguinis, and not to the blood corpuscles. Lo- comotive limbs sometimes absent; when present they are never fewer than three pairs, and may he very numerous. Ex. worms, insects, crabs, &c. 58. Mollusca or Heterogangliata. Animals possessing the Hetero-gangliate type of nervous system; that is, a nervous ring sur- rounding the gullet from which nerves radiate unsymmetricallyto be connected with other irregularly scattered ganglia. No definite type as to form of body; consistence generally very soft, hence 24 SYLLABUS, etc. named molluscans. Mucular skin or mantle. Many occupy cal- careous testse or shells, which may be univalve, bivalve or mul- tivalve. Others constantly naked; many immovably fixed to rocks, &c.; others with imperfect locomotive members. Appa- ratus of nutrition very complete; animal powers relatively low. Ex. Oyster, snail, cuttle-fish, &c. 59. Radiata, or Cyclo-neura, (cyelos, "a circle," and neuron, " nerve,") with a nervous system disposed with circular and radiate symmetry. A circular cord around the mouth, sending branches into each of the ray-like lobes, arms, or tentacula, given off from the body, or from around the mouth of the animal. According to Carpenter and others, the nervous ring has gangliform enlarge- ments opposite the base of each radiated appendage. But this is denied by Owen, who considers the nervous system of the Radiata to be characterized by the absence of ganglia, and hence he terms them nematoneura, that is, animals with a filamentous nervous system. Sometimes the whole body has the circular and radiate form, as in the Star-fish, but generally it is only the arrangement of the mouth and its tentacles, which conform to the type. In some of the Radiata, no nervous structure has yet been demon- strated, but their actions are such as to justify the inference that the elements of such a structure must exist in some form. These Owen proposes to erect into a special sub-kingdom under the name Acrita, that is, animals with an undiscernible nervous system. Examples. Star-fish, (nematoneurose,) Zoophytes, (Acrite). 60. Protozoa, or Aneura. Animals without any nervous sys- tem. Positive characters too variable to furnish grounds of dis- tinction. Some are destitute of digestive apparatus, and are also motionless, their vital powers, like those of plants, being directed solely to the performance of the formative operations, but they are yet regarded as animals on account of their general analogies of structure. Having no common type of form, they have been called Amorphozoa, but as the same may be predicated of molluscans, the proposed term is less distinctive than the preferred one, Protozoa, (protos, " first," and zoon, " animal,") indicating the lowest stage of animal life. SUB-DIVISIONS OF THE ANIMAL SUB-KINGDOMS. 61. The subordinate groups next in order to sub-kingdoms are termed Classes; which are divided into Orders; these into Tribes; and Families ; these into Genera, and these into Species, which last comprises all the individuals which may be supposed to have sprung from a common parentage. In presenting an outline of the anatomical characteristics of the principal classes of animals, it is better to begin with the lower and simpler forms, and to pro- ceed in the ascending series. syllabus, etc. 25 A. SUB-KINGDOM. PROTOZOA. I. Class--POLYGASTRICA. 62. Infusorial. Microscopic, from 24W5 inch (monas crepuscu- lum, in infusions of putrid flesh,) to 5V inch (Bursaria). Under the name Infusoria, given by Leuwenhook, they were confounded with Rotifer a of much higher organization. Appearance in their interior of a multitude of globular sacs, conceived by Ehrenberg to be multiple stomachs, and hence the class name. Ehrenberg's views contested by Meyen, Carpenter and others, who consider the sacs to be imperforate vesicles imbedded in a semi-fluid parenchma or protoplasma. They present an almost infinite variety of forms ; a distinct mouth armed, in a few cases, with teeth; a few have a separate anal outlet. Surface in most species beset to a greater or less extent, with fine vibratile cilia, fulfilling a three-fold use. (1) By creating currents of water, they bring food within the reach of the animal. (2) They subserve respiration by constantly chang- ing the water on the surface. (3) They propel the whole animal through the liquid medium. Skin tough, but very flexible, elastic and contractile. Some have Setae, or stiff, inflexible hairs as or- gans of support; others have uncini or hooked limbs. They multiply by fissiparous division; sometimes by gemmation, and finally by ovulation, when the water in which they are contained, is about to dry up, &c. This class is not a natural one, being composed of heterogeneous species. II. Class—Rhizopoda. 63. Protozoans of a very low grade of organization, most of which have this peculiarity, that their soft bodies are enclosed in calcareous or siliceous shells, with minute apertures, through which they project their pseudopodia (false feet,) which are long, thin, digitate prolongations of their soft body. These are used as means both of locomotion and alimentation. Being thus root-like in appearance and office, they give rise to the class name which means root-footed. Fossil remains of Rhizopoda of former epochs were called Foraminifera, from the apertures for the pseudopodia. Some of the shells are composite, each department containing a distinct animal, these are called Polythalamia, "many cham- bered." A few [naked or illoricated Rhizopods, as the Amoeba, Difflugia, §e., which project portions of their body so as extem- poraneously to construct their pseudopodia; without oral orifice they wrap themselves around their food, and apparently secrete gastric juice by their skin. Infusorial. 26 SYLLABUS, ETC. III. Class—PORIFERA. 64 The various forms of the sponge tribe are arranged into a distinct class under the above designation, which indicates a con- spicuous character common to them all, the perforation ot tbeir substance by very minute channels leading to a set of intercom- municating passages and excavations. Larger canals termina- ting in a set of larger orifices, the oscula, or vents, lwo distinct parts in the fabric of a sponge : namely, the fibro-corneous skele- ton, and the soft gelatinous flesh which clothes it. Structure ot skeleton, which in a few rare species is altogether siliceous like spun glass, but generally the fibres are of a leathery nature, with only a few siliceous spicules scattered through it. Naked eye and microscopic characters of the semi-fluid gelatinous parenchyma, which is made up of an aggregation of cells ToVo inch> ea°h ot which has the characters of a distinct proteiform or amoebilorm animalcule, having a certain power of spontaneous motion, obtain- ing and assimilating its own food, and altogether living by and for itself, except so far as it may contribute materials for the forma- tion of the fibro-siliceous skeleton." Vital phenomena exhibited by sponges. Multiplication (1) by ciliated gemmules, or detached portions of the gelatinous flesh, which transport themselves to distant spots, where they lay the foundations of new sponges ; and (2) by capsules, bodies of a larger size, and containing numerous globular bodies set free by the rupture of the capsule. These are probably true ova, and are developed towards winter, when the parent structure is about to die; a few fresh water species—all others marine. B. Sub-kingdom Radiata. I. Class—Polypifera or Zoophyta. 65. Definition.—Soft, inarticulate animals, mostly or wholly Acrite, consisting when single, of a body which forms the walls of a cylindroid cavity, the animal's stomach, closed at one end by a suctorial base, and terminated at the other by a circular disk perforated in its centre by a circular mouth, and giving origin around the latter to a series of radiating tentacula. It is, therefore, a mere self-moving stomach, with a single orifice for ingestion and egestion, fringed with sensitive and prehensile tentacula. Such structure is exemplified in the genera Hydra and Actinia, both of which are single and/ree. The former inhabiting fresh water, has its stomach excavated out of the general parenchyma,—the latter, a marine group, has a stomach with distinct walls suspended in an abdominal cavity. An immense majority of Zoophytes are com- posite, that is, a large number of individual polypi are connected SYLLABUS, ETC. 27 together by the fusion of the lower parts of their bodies, with a mass of gelatinous flesh common to the whole, called Polypary, the whole structure (Polypary and Polypi) being called a Polypi- dom. In a large majority of such genera the older parts of the polypary become calcified, when they are called Lithophytes, or consolidated with horny matter, when they are called Keratophytes. Sometimes the hard matter is deposited in the central axis, the fleshy matter bearing polypi being superficial, as in thecommon Red Coral. Sometimes the hard substance is external, forming tubes with the polypi emerging from the open ends (terminal) as the Tubipora Musica, (organ pipe coral,) or from orifices along their sides. 66. Ordinal sub-division. All the composite Zoophytes may be arranged in one of two groups, according as the individual polypi are Hydraform or Actiniform. (1.) Order Hydroida or Hydra- form Polypi. Composite forms mostly arborescent and tubular, with the hard matter rather horny or pergamentaceous than cal- careous. Multiplication by gemmation, fission and ovulation. (2) Order Actinoida, also called Anthozoa, "animal flowers," resembling the Helianthus, Anemone, and such like composite flowers, both in form and beauty of coloration. Tentacula tubular, open at the free end, and communicating by the other with the interseptal compartments of the abdominal cavity, which also have minute orifices opening into the stomach, whence they receive water to distend their bodies. Genus Actinia has species six or eight inches in diameters; other genera very small. Her- maphrodite, with distinct testes and ovaries, on alternate septa of the abdominal cavity. Multiply on a compound mass by budding. Colonies multiplied by eggs, or by detached buds. To this order belong, besides numerous other families, the Coralidse, Madreporidce and Madrephyllidse, which form the coral reefs and islands of the tropical seas. With the exception of the genus Hydra, found- in stagnant pools on aquatic plants, all the Zoophytes are marine. II. Class—Acaleph^: or Arachnodermata. 67. Synonymes.—Sea nettles—sting fish—jelly fish—sea blub- bler. Definition. Radiate animals of a jelly like consistence, generally translucent, or even of a glassy transparency, with a large preponderance of fluid constituents, which drain away when the animal is taken out of its native element, the sea, leaving only a light cobweb texture weighing only a few grains, when the perfect animal weighed as many pounds. Some are splendidly phosphorescent ; most sting and communicate this property to a limited quantity of water in which they lie for a short time, and to which they add a slimy secretion from their own bodies; great variety of forms ; community of digestive, circulatory and respira- 28 SYLLABUS, ETC. tory passages; sexes separate. Hence generation oviparous. Singular phenomena of alternate generation. 68. Ordinal division. (1) Pulmograda, or discophorous Medu- sans. Disk shaped; mouth inferior and four lipped, or else in the form of minute pores at the end of long-depending root-like appendages (as in genus Rhizostoma); locomotion effected by rythmical contractions of the margin of the disk, resembling the alternate contractions and dilatations of lungs, hence the ordinal name. (2) Ciliograda, moving by means of vibratile cilia. (3) Cirrhigrada, moving by means of the action of curled tendrils .or cirrhi. (4) Physograda, moving by reason of air vesicles, which they fill or empty at will. When distended, the animal rises by its buoyancy to the surface and is moved by the wind or tide, as Physalia utriculus (Portuguese Man of War.) III. Class—Echinodermata (spiny-sJcinned radiates). 69. The class name, indicative of a very conspicuous feature in the best known species (star-fish, sea-urchin, &c), resulting from the development of calcareous spines in their skin; but a great many animals now included in this class do not possess the cha- racter in question. Another character which is very common but likewise absent in some tribes, is the existence of tubular, retractile cirrhi, which serve as feet for some, and probably as respiratory organs for others. A still more common character, which is yet, however, wanting in a few, is the existence of calcareous plates (not the spines) in the substance of the skin, serving as a dermo-skele- ton. In default of any single universal artificial character, the class is recognized by the ensemble of natural characters. Whereas the polypifera have no respiratory channels, and only a few fami- lies exhibit the first traces of lacunar passages for the circulation of nutritive juices, and the acalephae have a community of diges- tive, circulatory, and respiratory channels, the higher radiates, designated by an inconstant artificial character (the prickly skin), really constitute a natural group, characterized by the possession of true blood-vessels with pulsatile walls at certain points, and of a respiratory apparatus, which in some is represented by the internal free surface of the peritoneum, and in others is a special localized apparatus. Nervous system distinctly radiate. Minute eyes found on the end of each ray of star-fish. Sexes distinct. Sexual organs multiplied. The number 5 and its multiples rem- nant in this class, as the number 4 is in the parallel class, Arach- nodumata, or acalephae. All are marine, and feed mostly on other animals. 70. Ordinal division. (1) Crinoidea or Pinnigrada, mostly fixed by a jointed calcareous stem to rocks, with the belly up- wards. But the Comatula, now known to be the mature condition of the animal, which, when fixed in its early state, is called Pen- SYLLABUS, ETC. 29 tacrinus Europseus, is free, and moves by flapping the pinnae or lateral barbs to its arms. (2) Ophiurida or Spinigrada, like the Ophiurus, crawl by means of short stiff spines. (3) Asteriada or Cirrhigrada, walk on solid surfaces by means of their suctorial, retractile cirrhi, projecting through the skin along the under surface of the rays. The stomach volumi- nous, and sends a pair of ramifying lobes into each of the five rays; which are, therefore, not tentacula or arms as are those of the two first orders, but merely lobes of the body. No anal outlet dis- tinct from the mouth as in the other orders. (4) Echinada or Spini-cirrhigrada, like the echinus (sea urchin), use both spines and tubular cirrhi as organs of locomotion. Their skeleton consists of ten meridian bands of calcareous plates, extending from oral to anal pole, and arranged in five pairs, con- sisting of tubercular plates, which bear long spines articulated with the tubercles by perfect ball-and-socket joints! with a muscular capsular ligament, alternating with five pairs of smaller bands the plates composing which are destitute of tubercles, but are perfo- rated for the locomotive cirrhi, and are called ambulacral plates. Other plates are disposed around the mouth and anus which are terminal and opposite, the anus being uppermost. The echinus has a very curious dental apparatus called Aristotle's Lantern. (5) Cystidea. Fossil remains recently discovered. Seem to have become extinct before the pentacrinites were called into exist- ence. Combine some of the distinctive characters of the Crinoidea, Ophiurida, Asteriada, and Echinida. (6) Holithurida or Cirrhi-vermigrada, like the Holithuria, have cirrhi in varying number, for different genera, and variously disposed ; elongated bodies, and very muscular skin; hence vermi- grade in water, and cirrhigrade on a solid surface; tentacula around the mouth; calcareous ring around the mouth, at the base of tentacula; respiratory tree opening into anal cloaca ; genital ap- paratus wTith single outlet, &c, &c. (7) Siponculida or Vermigrada. No cirrhi; no calcareous plates or spines ; but internal organization strikingly similar to that of the Holithurida. C Sub-kingdom. Mollusca or Hetero-gangliata. I. Class—Bryozoa (animal moss.) 71. Microscopic, or very minute; generally found in composite masses like true Zoophytes, of which the polypary is either a creeping stem, or an aborescent trunk, or an irregular mass. Formerly confounded with true Zoophytes, as a sub-class termed Ciliobrachiata, their tentacles being fringed with vibratile cilia. Each individual composed of an external sac of which the outer 30 syllabus, etc. layer is either membranous, or horny, or rarely calcareous ; ar- rangement of retractor muscles for drawing the mouth and tentacles into the tube and closing its orifice. Internal organization mol- luscan as respects digestive apparatus. They are the only mol- lusks without a distinct circulatory apparatus ; ciliated ^ tentacula probably organs of respiration as well as of alimentary ingestion; a single nervous ganglion between mouth and anus, which are near together, representing the lowest grade of Heterogangliate type. Propogation by attached buds growing on the polypary mass; colonies multiplied by ova, developed and fertilized by the same individual, the Bryozoans being hermaphrodite. II. Class—Tunic at a. 72. Body inclosed in a tunic or leathery bag quite distinct from the muscular mantle, and rather to be compared with the calcareous shells of the conchiferous species, being very tough, and sometimes having grains of sand agglutinated on its surface. Two orifices op- posite to and corresponding with the oral and anal outlets of the true body of the animal. The oral opening in the tunic surrounded by short, radiating and ciliated tentacles, the anal separated from the true anus by a cloaca into which the genital passages also open. The tunic connected with the mantle at these orifices. Dilated Pharyux serving also as a respiratory sac, the surface bUVeen,« divided by regular folds and every where studded with respiVatory cilia. Digestive apparatus similar to that of Bryozoa. A distinct circulatory apparatus consisting of a muscular heart with one cavity, alternately systemic and branchial, and two sets of vessels without valves, and each being alternately arterial and venous. Single nervous ganglion as in Bryozoa. Like the latter, many tunicata form composite masses. Two orders. (1) Ascidiform, embracing the single and the compound Ascidians. Both kinds fixed to rocks; the compound forms being developed from single individuals by continuous budding from a common stalk. (2) Sal- pidse, also embracing single and compound forms, both of which are free, and move by means of currents of water discharged from their respiratory chambers. In the compound forms, the aggre- gated individuals have no organic continuity, but adhere pretty firmly by means of little suckers. Not identical with solitary individuals. A solitary salpa developes in its body an internal stolon, (having no true sexual organs,) from which buds sprout out, and are developed into an aggregated mass of which the separate individuals are of different sexes. Sometimes a whole chain consists of males, and others females. The product of true generation between the sexes is always a single salpa without sexual organs, but de- veloping the internal stolon. Thus every alternate generation is a composite mass, and only at the intervening stages do the solitary individuals appear. syllabus, etc. 31 III. Class—Brachiopoda, or Palliobranchiata. 73. Bivalve acephalous mollusks, in whom the entire mantle serves as a branchial or respiratory organ, by having the branchial vessels distributed over it. In other respects the internal organi- zation is sufficiently analogous to that of the following class to render it unnecessary to enter into details. The two long arms fringed with filaments that spring from either side of the mouth are neither prehensile nor locomotive instruments, but by means of the cilia clothing their surfaces, they create currents in the water for injestion and respiration. IV. Class—Lamellibranchita. 74. Also bivalve and acephalous, and by reason of their impor- tance among the acephalous classes, are frequently designated simply Acephala, as if this were a class peculiarity. The proper class name derived from a specialized respiratory apparatus in the form of. four membranous lamallae or leaves lying between the lobes of the mantle and fringing the body of the animal. Valves (separate pieces of the shell) connected by a hinge and an elastic ligament; closed by the action of one or two adducter muscles, pulling the valves into close contact and compressing the liga- ment. Valves lateral with hinge on the dorsal side. Many bivalves fixed, by adhesion of one or both valves to solid bodies, or by a tendinous cord, or mass of horny filaments, the Byssus. Others are free; some float; others leap or crawl by means of a muscular " foot" which, with others, is a boring instrument. Some have mantle open, (Ostracea). Others have the two lobes of the mantle more or less completely united, having in some cases simple apertures, and in others, syphonous tubes for respiration and defecation. Very large liver, as the dark part of the Oyster. Two- cavitied heart always systemic, and frequently perforated by the rectum. Most are dioecious, the genital parts lying back of the heart. A pair of oesophageal nervous ganglia communicating by cords over the gullet. Branchial ganglia. Pedal ganglia in those species which have a foot. One genus, Pecten, supposed to have ocelli around the margin of the mantle. V. Class—Gasteropoda. 75. Mollusks whose instrument of locomotion is a muscular disk on the under surface of the belly. Very extensive class in which a few species are naked, but most have univalve testaceous shells, of which the typical form is a cone with expanded base, as in the Patella, but most frequently the axis is spirally disposed. For 32 SYLLABUS, etc. structure and mode of growth of testaceous shells generally, see Carpenter, loc. cit. §§ 280 and 281. Internal organization of Gasteropods considerably higher than that of any of the acephalous classes. Distinct head and organs of special sense. Ganglionic nervous matter above as well as at the sides of the gullet. Numerous orders mostly artificial. Order Pulmonea is however natural, exemplified in the genera Helix (snail) and Limax (slug) which have a respiratory air cham- ber with vascular walls. The members of this order are Herma- phrodite, with very complete organs of copulation ; not capable of self-impregnation; most of the other orders are dioecious. VI. Class—Pteropoda. 76. Mollusks with a wing-like membranous expansion on each side of the neck, by means of which they swim through the water with great activity. « Should, perhaps, be regarded rather as an aberrant subdivision of the Gasteropoda, than as a distinct class," and have no special physiological importance or point of interest. VII. Class—Cephalopoda. 77. Mollusks whose feet or locomotive appendages are attached to the head. These same appendages are also instruments of \ prehension, being armed with powerful suckers. In many, all the internal organs are collected into what may be called the head; so that the entire animal is a large head, from the under side of which there projects a thick circular membranous expansion, which divides into the long powerful arms that serve as feet when the animal crawls on a solid surface, with the mouth in the centre of the disk, downwards. Respiratory chamber in front of abdominal cavity, with syphonous outlet; the forcible discharge of water through which serves to propel the animal backwards. Approxi- mation to vertebrates in the concentration of vesicular nervous matter above the gullet, and in having a rudimental cranium of cartilage. Two orders.—(I)Tetrabranchiata. Nautilus, the only known existing genus or species. (2) Dibranchiata, exemplified by the genera Octopus, Sepia, Argonauta, Sfc, §c, which possess an ink-bag, not present in the nautilus. The general organization indicates a higher grade of animal existence than that of other molluscan orders. For arrangement of nervous ganglia see Car- penter, loc. cit. § 854. SYLLABUS, ETC. 33 D. Sub-kingdom. Articulata or Homogangliata. I. Class—Entozoa. (Internal Parasites.) 78. As the class name and the definition merely indicate the habitation of the species, it was a priori probable that, like the Infusoria, the group would prove not to be a natural one. Some Entozoa are Protozoans, some Radiates, and even the highest forms only indicate a tendency towards the articulate type, few, if any, ever attaining to the higher steps of the development. Yet there is some convenience in treating them as one group. ORDINAL SUB-DIVISIONS OF THE CLASS. 79. Order I. Cystica, of which the simpler forms are mere animal cells, and therefore incontestably Protozoan. Best known genera and species found in the human being are (1) Acephalocys- tis Endogena, (Hydatid) a headless cyst, or mere organic cell of large dimensions, containing other and smaller ones, the product of endogenous development. (2) Echinococus hominis, or parent acephalocyst, filled with albuminoid liquid in which float little animalcules, consisting of a mere head with a circle of hooklets and four suckers. (3) Cysticercus cellulosse, having a head and neck like the genus Taenia in the following order, and with an enlarged cyst for its body and tail, whence the generic name, which means a cyst-like tail. Another genus having some points of analogy with the two last, but not found in man, is (4) Grnurus, which is an acephalocyst with a large number of taenia-like heads project- ing off from its walls, and organically connected with them. The parent vesicle thus appears like the common tail of all these heads, whence the generic name. The Cosnurus Cerebralis is found in the brain of sheep and causes a fatal disorganization. 80. Order II. Cestoidea, which means fillet-like. Two species belonging to different but closely allied genera found in man; namely, (1) Taenia solium, having a head like that of Coenurus or Cysticercus, which are quite probably abortive taenia with dropsical bodies. Articulate form—multiplication of genital appa- ratus, male and female, in each individual; opening on the margin of the flattened segments, on opposite sides of those that are con- tiguous. The history of the development of its innumerable ova is not ascertained. (2) Bothrio-cephalus Latus, distinguished by the two longitudinal fossae on the head, and by the genital organs opening in the centre of the surface of each segment instead of on the margins. 81. Order III.—Trematoda, which indicates as a character- istic the fact that the body has other openings besides that of the mouth and anus. This character is, however, in all probability, 3 34 SYLLABUS, ETC. illusory, and at all events it is unimportant. Still the order is retained on account of well-marked peculiarities of organization, which are likewise exemplified in certain non-parasitic aquatic worms the Planariae. These accordingly are placed in this order. Mouth in the centre of a suctorial depression sometimes found on a projecting proboscis, at some distance from anterior end of the body. Stomach generally with ramifying lateral appendages. Distinct circulatory system consisting of but few trunks, them- selves very small, and a minute net-work of capillaries. Organs of generation more localized than in the Cestoid order. Pair of ganglia anterior to the mouth, and indicating an arrangement somewhat intermediate between the molluscan and articulate types. In the lowest forms the cords from these ganglia diverge, as in molluscans. In the higher species they approximate towards the median line on the ventral aspect. The only genus known to infest the human tissues is the Distoma or Fasciola ; as (1) Fasciola Hepatica (formerly called Distoma Hepaticum) or Liver Fluke ; and (2) Fasciola Lanceolata, both species being found in the liver and gall bladder. 82. Order IV. Acanthocephala (Prickly headed.)—None found in man. Echinorhynchus Gigas of the hog, a most formi- dable parasite. 83. Order V. Nematoidea.—The entozoa of this order have a decidedly higher organization than the preceding. One distinc- tive trait is the existence of distinct walls to the alimentary pas- sages, whereas in the preceding these passages seem to be mere excavations in the general parenchyma. Hence the latter have been designated as a distinct Radiate class Sterelmintha (solid worms,) while the Nematoid order has been elevated to a separate class called Cohlelmintha, (Cavitary worms). Other features of their organization exemplified by the Ascarls Lumbricoides, the common round worm. Sexes distinct, female being always larger, and having near its middle a circular constriction at one side of which is the vulva leading by a vaginal tube to the so called uterus, the dilated portion of the tube at the junction of the two ovarian tubes whose convolutions fill the hinder part of the body, except the axis, which is occupied by a straight intestinal tube. Male with an erectile intromittent spiculum projecting from the end of the tail. Lowest grade of articulate type of nervous system, namely, small supraoesophageal ganglion with ventral cord desti- tute of ganglia on it. Table of Human Entozoa. 84. I. Sub-Class—Protelmintha. (1) Acephalocystis Endogena, . . Liver and peritoneal cavity. {■!) Echinococus Ilominis, . • Liver, spleen, omentum. (.-;) Cysticercus Cclluloscc, . / Areolar tissue between the fasciculi of ( muscles—eye—brain. SYLLABUS, ETC. 35 II. Sub-class—Sterelmixtha. (4) Tccnia Solium, ) (5) liothriocephalus Latus, / (TaPe worm) Small intestines. (6) Fasciola Hepalica, \ (7) Fasciola Lanceolata, / • • Liver, gall-bladder, &c. III. Sub-class—Ccelelmintha. (8) Trichina Spiralis, . . Voluntary muscles. (9) Filaria Mcdinensis, (Guinea worm) Sub-cutaneous areolar tissue. (10) Filaria Oculi humani.. (11) Filaria Bronchialis, (12) Tricocephalus l)ixpm\ (13) Spiroptera Hominis, . (14) Strongylus Giyas, (15) Ascaris Lumbricoides. (16) Ascaris Vermicularis, Crystalline lens. Bronchial glands. Caput coli. Urinary bladder. Kidneys. Intestinal canal. Rectum. II. Class—RoTIFERA (wheel animalcules.) 85. Infusorial Articulates of microscopic dimensions, from -J- to too inch; characterized by the presence, in most species, of one or more fleshy lobes near the mouth fringed with vibratile cilia, having, when in action, the appearance of revolving wheels: when at rest the wheels are retracted as if the animal had swal- lowed them. Their use as means of ingestion. A few loricated species—skin exceedingly flexible and contractile with scarcely a perceptible trace of segmental division except in the tail, where there are several segments sliding upon one another in telescope fashion; curious dental apparatus at the bottom of the oesophagus; narrow stomach and straight intestinal tube dilating into a cloaca. Respiratory(?) syphon. Low development of Homogangliate type of nervous system. Ocelli in some species. III. Class—Annelida, or more properly Axnellata. 86. Vermiform Articulates, many of which are entirely apodal, while the others have only rudimentary inarticulate limbs; all breathe water except the members of one tribe, which breathe moist air; in most cases their blood is coloured; there is a much higher development of both vascular and nervous systems than we find in the highest entozoa which they resemble otherwise very closely. Except one order all are aquatic and most are marine. Ordinal sub-divisions. (1) Dorsibranchiata with dorsal branchial tufts generally coloured; very elongated segmental body, the segments being all alike except the terminal ones. Dorsal and ventral oars with a bundle of setae on each side of bWfy of the segments. (2) Tubicola 36 SYLLABUS, ETC. resemble the last, except that being enclosed in a tube, they have no locomotive oars, and the branchiae are concentrated around the head. Hence have been called Cephalobranchiata. (3) Terricola includes the terrestrial and aquatic species. Thus the Lumbricus, common earth worm, lives in moist earth on land. The Arenicola which has dorsal branchiae, but in other respects resembles the Lumbricus, lives in the sand under sea-water; organization lower than that of preceding orders, and resembles that of the Nematoid Entozoa. (4) Sucto.ria—as the Hirudo medicinalis (medicinal leech) whose organization resembles that of the Trematoid Entozoa; but yet they have a well developed homogangliate nervous system, the brain being connected with five pairs of optic nerves, and minute ganglia being developed on the ventral cord; three sharp saws in relation with the mouth for making their peculiar triradiate puncture. IV. Class—Myriapoda. 87. Air breathing articulates, with elongated bodies divided into numerous similar segments, each of which except the terminal ones bears one or two pairs of articulated but generally feeble limbs. Integument more or less consolidated by Chitine into a somewhat firm dermo-skeleton. Respiratory apparatus tracheal like that of insects which they resemble in other features also of internal organization, except that in the lowest family, (Julidce) the genital apparatus opens near the anterior part of the body. Two orders. (1) Julidae, having for its typical genus the Julus (millepede) with very numerous segments, (40 to 80 in the perfect animal) each of which has two pairs of short and feeble legs. Segments cylindroid and dermo-skeleton not very hard. Development in early life consists mainly in multiplying the number of segments. (2) Scolopendridae having the Scolopendra (centipede) as its typical genus with from 12 to 22 segments. The Scutigera Longipes (the common house centipede) belongs to this tribe. Genital apparatus opens behind as in insects. V. Class—Insecta or Hexapoda. 88. Articulates with tracheal respiration and three pairs of lcu* segments of the cranium of all the elements of a true vertebra. These cranial vertebrae are, (1) occipital with haemal or scapular arch dis- placed in all vertebrates except the Osseous fishes—the vertebra of audition; (2) the Parietal or Gustative vertebra with the Hyoid apparatus for its haemal arch; (3) Frontal or Optic verte- bra with lower jaw for the haemal arch, and (4) Nasal or Olfactory vertebra with the upper jaw for the haemal arch. The parts which complete these vertebrae comprise all the bones of the cranium and face, except the Petrosal, the Ethmoidal, (lateral masses of the Ethmoid,) Inferior Turbinated and Os Unguis, which are parts of 46 SYLLABUS, ETC. a splanchno-skeleton. In most vertebrated animals we find a cer- tain number of hard pieces, generally bony, sometimes cartilagin- ous, or fibrous, or horny, which do not properly belong to the endo-skeleton, although in a few cases some of them may, for cer- tain adaptations, be intercalated among the proper segments of the endo-skeleton. Some being more or less closely connected with the external skin, seem to be detached pieces of an incomplete dermo- skeleton, while others being integral constituents of certain impor- tant organs or viscera rather than simple protectors of such viscera, are termed Splanchno-skeleton. The principal pieces of the splanchno-skeleton in higher vertebrates are, (1) Petrosal bone or Ear capsule ; (2) Sclerotic capsule or Eye capsule ; (3) Ethmo- turbinal or nose capsule; (4) Dental apparatus ; (5) Vocal and bronchial apparatus, &c. The dermo-skeleton is represented by hair, feathers, scales, bony scutes, &c. In man the os unguis seems to be the only trace of an ossific portion of dermo-skeleton. It is only in the higher mammalia, whose large brain required an expanded cranium, that the pieces of splanchno-skeleton (Petrosal and Ethmoidal,) are intercalated among the cranial parietes. Brief notice of the several regions of trunk vertebrae, as (a) cervical region; (b) thoracic region ; (c) lumbar region; (d) sacral region ; (e) caudal or coccygeal region. / ■ . ' - .'I. Class—Pisces. 101. Cold-blooded vertebrates, breathing water by means of gills, to which the whole of the blood is sent from a single ventricle, and from which it is distributed to the system before it is returned to the heart, which is thus exclusively pulmonic, may be divided into three sub-classes. (1) Dermopteri, including all the soft, apodal fishes whose exo- skeleton and vertical fins have no really hard pieces, either bonv or cartilaginous, but are simply muco-dermoid in structure, and whose endo-skeleton is unossified. Two orders, (a) Cirrhostomi, represented by the amphioxus, a very aberrant animal, having a longitudinal mouth with lateral cirrhi; (b) Cyclostomi, represent- ed by the Myxina,-/Hag), and Petromyzon, (Lamprey), with circular sucking indutBs. (2) Sub-class. Osteopterygii, (Osseous Fishes) consisting of all those fishes which have the endo-skeleton more or less completely ossified. Includes six Cuvierian orders, namely, (a) Acantho- pterygii, (spiny-finned); (b) Malaco-pterygii abdominales; (c) Ma- laco-pterygii Sub-brachiati; (d) Malaco-pterygii Apoda; (e) Lo- phobranchii; (f) Plectognathi. (3) Sub-class. Chondropterygii (Cartilaginous Fishes) have the highest organization of the whole class. Two orders (a) chon- dropterygians with free branchiae, as sturgeons, &c- ; and (b) with fixed branchiae, as sharks, &c. SYLLABUS, ETC. 47 102. External forms of Fishes. Two sets of fins in most of the class, namely, vertical azygous fins and oblique fins in pairs; the latter never exceeding two pairs, one diverging from the scapular arch, the other connected with a rudimental pelvic arch, which may be placed either at the normal position, (abdominales) or under the throat, (Jugulares) or at intermediate positions, (Thora- cici). The impair or azygos fins are dorsal, (one or two); Anal just behind the anus ; Caudal, which may be Homocercal, that is, vertically symmetrical, an upper and lower piece being similar, and separated by a notch ; or Hetero-cercal, as found in the carti- laginous fishes where the rays of the caudal fin are connected with the bodies of several caudal vertebrae, which run exclusively into the upper lobe of the fin, the lower being much shorter. Large gill openings behind operculum. Lateral line of pores, orifices of mucous glands. 103. Peculiarities of the Piscine Skeleton. No medullary canal in the long bones. No regular system of haversian canals and cancelli, but large, irregular, angular lacunae with few but large radiating canaliculi. Bodies of vertebrae generally with cupped surfaces, working over convex intervertebral capsules. Very gradual development of the vertebral axis, from being a mere cel- lular and gelatinous " Chorda Dorsalis," without segmental divi- sions, as in the Amphioxus, to the condition found in Lampreys, where cartilaginous laminae are developed within the folds of a fibrous membrane surrounding the Chorda Dorsalis, and which by the separation of its two layers above and below constitute the neural and haemal arches in the Myxinoid family. Vertebro cranial axis divided into only three regions in most fishes, namely, Cranial, Dor so-abdominal and Caudal, there being no neck, or sacrum, and no distinction between Thoracic and Lumbar regions. In the Squalidae, however, there is a cervical region. Use of Pec- toral and Pelvic extremities. Structure of hands with its numer- ous rays indicating, however, mere irrelative repetition. Ribs attached to transverse processes, or to vertebral bodies. No sternum. Peculiarities of the cranium and face. 104. Dermo-skeleton.—(1) Skeleton of the vertical fins either un- jointed bony spines, (acanthopterygii) or else articulated cartilagi- nous rays, (malaco-pterygii) resting upon and articulated by a chain link joint with the dagger-like interspinous bones. (2) Sub-orbital, supra-orbital, supra-temporal and labial scale-bones. (3) The more common scales, whether ossified or not, lying between cutis and cuticle, in a depression of the former. Four varieties of scales. Placoid, Ganoid, Cycloid and Ctenoid on which Agassiz founds his ordinal division of the class. 105. Splanchno-skeleton.—In addition to the more common pieces we note, (1) Branchial apparatus, consisting of the branchial arches, four in number, attached below to basi-branchial bones, and above to the cranium ; toothed on their opposed surfaces. Branchiostegal rays diverging appendages of Hyoid arch. (2) 48 SYLLABUS, ETC. Pharyngeal bones behind branchial apparatus, often armed with teeth. (3) Oral teeth, often very numerous ; generally mere cal- cified papillae, whose base is consolidated with the bones on which they rest. 106. Alimentary apparatus the simplest consistent with the vertebrate type. Pulmonic bilocular heart with bulbus arteriosus, looking like a third cavity. Four gills on each side, in most fishes, receiving all the venous blood, and transmitting all the arterialized blood, without a second return to the heart, directly to the system, by the union of the branchial veins into an azygos dorsal artery after the head has first received its special vessels from the upper- most branchial veins. The ovaries of the female, known as the roe, occupy at the breeding seasons much the greater part of the abdominal cavity ; ova escape into the ovarian sac, to be extruded prior to fertilization, which is subsequently accomplished by coming in contact in the water with seminal matter discharged by the male in a similar way from testicles occupying a similar situation. Fishes have cold blood with elliptical blood disks. II. Class—Amphibia. 107. Cold blooded vertebrates with naked, skin, most if not all of which in the early larval stage of their active existence have the anatomical and physiological characteristics of fishes, but sub- sequently undergo a metamorphosis one result of which is the development of lungs for breathing air, though a portion of the class retain their gills also, so as to be permanently amphibious in their powers of respiration. This section of the class termed Perennibranchiate. The others, named Caducibranchiate, lose their gills when they acquire lungs, and assume most of the reptilian characters. Hence by many zoologists the class Amphibia is ranked as a mere ordinal sub-division of the class Reptilia, under the name Batrachia. Reasons for rejecting this classification. Ordinal sub-divisions. (1) Anoura, which during metamorphosis lose the tail that previously was long and com- pressed. Other characters of Tadpoles. Branchiae, in some species drawn into the cheek before metamorphosis. Impregnation effected ' externally during the extrasion of the ova. Common genera in this order are Rana (Frog) and Bufo (Toad). (2) Urodela.—Tail long and persistent, rounded in Salamandra, compressed in Triton. Feet, always four. Ribs very short. Vertebrae numerous and movable. Tympanum concealed. Impregnation internal. Com- mon genera are Salamandra and Triton, the latter retaining the gills much longer than the former. To this order are generally assigned also the Menopoma and Amphiuma, which, however, are not knoton to possess branchiae at any period of their existence, and hence Bell proposes to place them in a separate order under the designation Abranchia, but it is by no means certain, as he SYLLABUS, ETC. 49 himself admits, that these genera undergo no metamorphosis. (3) Apoda.—Body elongate; slender; eel-like; without feet; tail very short, almost wanting; one lung larger than the other; sternum wanting; ears concealed; genus Caecilia. The three foregoing orders constitute the Caducibranchiate section. The Perennibran- chiates are all included in one order, named Branchifera (Cuvier) I ! ♦ or Amp&in^urta (Bell) with bodies elongate, formed for swimming ;* r\L feet eithW Your or two anterior only; tail compressed, persistent, U/>7cl branchiae external, persistent and coexisting with rudimen- ; ; tary lungs. Genera, Proteus, Siren, Menabranchus, Axoldij. ■?-.* ^ '; Changes in the arrangement of the branchial circulation coinciding with the metamorphosis; circulation now substantially reptilian, but differs by the permanent retention of the branchial vascular arches which unite to form the dorsal artery. Blood disks ellip- tical and very large. III. Class—Reptilia. 108. Vertebrates with cold blood, pulmonary respiration, tri- locular heart (in the single ventricle of which the two kinds of blood received from the two auricles are mixed, to be distributed in part to the system, and part to the lungs,) and skin covered with hard and dry cuticle, forming in some imbricated scales, and in others broad plates. Blood disks ellipical. Ordinal divisions. (1) Chelonia or Testudinata, covered with broad horny shells, exhibit a most remarkable consolidation of the skeleton. Dorsal carapace formed of spinous processes of dorsal vertebrae and the ribs. Sternal Plastron formed of expanded sternum and some dermal pieces. Head, tail and limbs of many species may be withdrawn into the box formed by the carapace and plastron, the latter being sometimes jointed in the middle. Scapular and pelvic arches lie within. Edentulous, but have sharp, horny beaks. Feet unguiculated with or without webs, or else enclosed in a paddle-like fin. (2) Order Ophidia, covered wTith scales. United by Bell with the Lacertidoe of the next order, under the designation of Squamata, which he contends is a more natural arrangement than the one commonly adopted. Skeleton remarkable for multiplication of trunk vertebrae (400 in Python) connected by a very moveable ball-and-socket joint; moveable ribs ; no sternum ; no locomotive members, and only in a few an imperfect pelvic arch. Head remarkable for the looseness of the connection between the bones that surround the mouth. Even the Tympanic pedicle and the mastoid bone to which it is chiefly attached, hang very loosely. Numerous small conical teeth of non-venomous species found in both jaws. Venomous serpents have two large poison fangs on the front of the upper jaw. (3) Sauria.—Separating the Lacertidae, which like serpents, are covered with imbricated scales, and which are closely connected 4 50 SYLLABUS, ETC. with true serpents by an osculant group, the Saurophidia, that are apodal but otherwise Lizard-like, the remainder of the Saurian order may be designated by the term Loricata, as being covered with bony scutes. Peculiarities of the Saurian type of skeleton demonstrated by means of drawings and actual preparations; alimentary apparatus; structure of lungs. Heart with four cavities in the crocodile, mixture of venous and arterial blood outside of this heart, the head receiving pure blood. Generation oviparous in all reptiles, though in some species the eggs are occa- sionally hatched in the oviducts, simulating viviparous generation. IV. Class—Aves. 109. Oviparous vertebrates with warm blood, double circulation and double respiration; anterior or pectoral extremities organized for flight; body covered with feathers ; mouth edentulous; blood disks elliptical. Ordinal sub-divisions. (1) Raptores or Accipitres, with very strong talons, armed with sharp, hooked claws ; beak also hooked and sharp, as eagles, hawks, owls, and other "birds of prey." (2) Insessores or "perchers" with feeble and unarmed toes, one di- rected backwards and three forwards. Beak generally pointed and not vaulted above ; wings long and body erect. Swallows, larks, and the most common birds. (3) Scansores "climbers," two toes directed backwards and two forwards. Beak and wings as in the Insessorial order. (4.) Gallinaceae or Rasores (scratchers) supe- perior mandibles arched or vaulted ; nares partly covered by a soft, inflated scale; gait heavy; wings short; toes as in the Inses- sorial order ; but generally the nails are more blunt, and the males of some genera have a spur. Common fowl, partridge, pheasant, &c. (5) Grallatores, "waders," feet formed for wading; tarsus and metatarsus being very long, and the lower part of the leg naked. Crane, heron, snipe, woodcock, &c. (6) Cursores "run- ners," included by Cuvier in the preceding order, from which they differ, however, by the rudimental condition of their wings, which, when most fully developed, are still only fit for beating the air while the body is borne along by the rapid progression of the legs reacting against the ground, as in the ostrich. One genus (Apteryx) found in New Zealand, has only a scarcely discoverable rudiment of a wing on each side. (7) Natatores or Palmapedi, "swimmers;" web-footed; legs generally placed far back, render- ing swimming easy but walking difficult. Several genera, as ducks, geese, &c, have their beaks covered with a soft skin. 110. Anatomical peculiarities of Birds. General shape of body and its several regions. Epidermic appendages, feathers, pe- culiar to the class ; their form and structure. Cranial bones very early consolidated; upper jaw slightly moveable, with its lower jaw edentulous but covered with a horny beak. Tympanic bone SYLLABUS, ETC. 51 still separate and moveable, as in all other oviparous vertebrates. Cervical vertebrae from 9 to 23, and very moveable with double diar- throdial joints separated by a meniscus. Anchylosis of dorsal vertebrae. Bony sternal as well as vertebral ribs ; extensive keel- shaped sternum in most birds, but nearly flat in the ostrich. Lumbar and sacral vertebrae soldered together and to the ossa innominata; pelvic arch incomplete below; scapular arch very firm and composed of a narrow rib-like scapula, lying parallel with the spine, and a thick strong coracoid, articulating by a strong joint with the ster- num, so as to form a rigid buttress which prevents the shoulders from being drawn together by the powerful traction of the pectoral muscles. The two clavicles unite in front of the coracoid to form the furculum or merrythought; two carpal and two tarsal bones; three metacarpals partially united ; three fingers; from two to four toes, most commonly the latter, of which the first looking back- wards has two phalanges, the second has three, the third has four, and the fourth has five. Digestive Apparatus. Mastication effected by the agency of the wall of a special stomach, called the Gizzard, lined internally by a hard, horny cuticle, the walls being formed chiefly of very strong muscles, whose fibres radiate from two central tendons. Use of the pebbles swallowed by graminivorous birds. Ingluvies or crop and Proventriculus, with its walls studded with gastric glands, both being in front of the gizzard. Small and large in- testine ; cloaca ; very large, and more or less symmetrical liver, &c, &c. Circulation double as in man ; blood warmer than that of mammals; blood disks elliptical and greatly smaller than in fishes and reptiles. Respiration double, that is, the blood besides being aerated in the lungs, is also partially exposed to the air in the sys- temic capillaries in most regions of the body, by means of air sinuses communicating with the lungs. Final causes of this ar- rangement. In both sexes the genital tubes open into a cloaca. Males generally destitute of an intromittent organ; copulation being effected by simple juxtaposition of the sexual orifices, by an eversion of the cloaca. Some aquatic birds have a true penis, which, when lax, is withdrawn into the cloaca, but projects when erect, and is grooved for the transmission of the semen. V. Class—Mammalia. 111. Warm blooded vertebrates, having viviparous generation, with which there is invariably found to coincide the presence of mammary glands, on the secretion of which the new-born mammal is fed. Circulation double and complete. Respiration complete but single. Body invested more or less completely with hairs, or some homologous modification of epidermic cells, except in a few naked species. Two sub-classes. I. Placentalia with a truly viviparous generation; the young being born in a comparatively 52 SYLLABUS, ETC. matured state, after having been connected with the mother by means of a placenta. II. Implacentalia with only ovo-viviparous generation. In this case, although a living embryo is extruded, it is very immature, never having had a placental connection with the maternal system, and is consequently destined to lead an ex- clusively organic life for some time after birth, during which it is firmly fastened by its mouth to the maternal teat. Ordinal Sub-divisions. I. Sub-Class—Placentalia. 112. (1) Rodentia; (gnawers); two front teeth in each jaw, chisel-shaped for gnawing, covered by enamel only in front; variable number of molars. Squirrel; rat. (2) Edentata (without teeth); wanting either all the teeth or having only imperfect molars. Ant-eater, armadillo, sloth. (3) Ruminantia, which ruminate or chew the cud. Hoofs cleft; except the camel tribe all want incisors in the upper jaw; the most common dental formula being, incisors, f, no canine; molars |-|; with the same exception, all have horns, at least in the male sex. (4) Pachydermata or thick-skinned mammals, comprise four tribes, viz.: (a) P. Proboscidea, as the elephant, (b) P. Ordinaria as the hog, &c. (c) P. Solidungula, with a single digit in each foot, as the horse; and (d) P. Cetacea Herbivora, as the du- gong, &c. (5) Cetacea ; posterior extremities wanting; anterior converted into swimming paddles; horizontal tail-fin: some have a dorsal vertical fin. Fat, called blubber, in the very substance of the skin. Nostrils on the top of the head, by which cetaceans spout. Peculiar disposition of vascular sinuses in adaptation to their habit of remaining submerged for some time; whales, porpoises, &c. (6) Carnivora, or beasts of prey, comprising three tribes, viz.: (a) Digiligrada, as the Fdidce or Cat tribe, and Canidce or dog tribe. In the former, retractile and sharp claws, and peculiar carnivorous teeth . Claws of Canidae blunt and not retractile, (b) Plantigrada with teeth partly adapted to vegetable diet, as bears, (c) Amphibia or Phocidee, with forms adapted for residence in water. Seals. (7) Insectivora.—Special conformation of teeth adapting them for crushing hard skins of the coleoptera. Moles, shrews, &c. (8) Cheiroptera, (winghanded) anterior extremities organized for flight by enormous elongation of fingers, which support a delicate duplication of skin. Teeth irregular. Bats. (9) Quadrumana, with opposable thumbs on all four of the extremities, (at least in most of the genera) all being prehensile SYLLABUS, ETC. 53 as well as locomotive members. Dental formula in most of the families the same as in man; but some have an additional molar on each side of each jaw. Monkeys and apes. (10) Bimana—Anterior extremities organized exclusively for prehension, terminating in hands of which the opposable digit is a more perfect thumb than we find on any of the extremities of Quadrumana. Man, the sole species of this order. II. Sub-Class—Implacentalia. (11) Marsupialia, (pouched animals). Young born very immature, and conveyed in some way to the marsupium or abdominal pouch of the mother, where they grasp the teats with their mouths so firmly as to appear organically united. Marsupial bones and their use in the two sexes. Uterus and vagina double and open into a uro-genital canal, which has a common opening with the rectum, but there is no true cloaca. Opossum, kangaroo, &c. (12) Monotremata.—Implacental mammals with a cloaca com- mon to the uro-genital canal and to the rectum. Even in the male, the uro-genital canal opens into the cloaca, but the penis is perfo- rated, and during erection has its hinder orifice drawn to that of the uro-genital canal, so as to receive the semen which is projected through numerous papillary orifices on its free end. Two uteri and vaginal canals, which are quite separate on the two sides, and open by separate orifices into the uro-genital canal. A very aberrant group, resembling birds in several other respects, besides the dis- position of the genital organs. Only two known genera, namely, the Ornithorhynchus (Duck-bill) and Echidna, covered with strong spiny bristles, which it can erect like a hedge-hog. Found only in New Holland, where also all the existing marsupialia reside, except the Didelphys (opossum) which is only found in America. 113. Anatomical peculiarities of Mammals—Two pairs of ex- tremities present throughout the class, except only in the true Cetacea and the Cetacea Herbivora, which lack the hinder extremi- ties, and have only a rudimental pubes. In all, the head is marked off from the trunk by a neck, though this is much obscured in the fish-like Cetaceans. All except Cetaceans more or less completely covered with hair, sometimes modified in a very extraordinary way, as in the quills of the Porcupine, or the imbricated scales of the Pangolin, or in the ossified plates of the Armadillo, or in wool, which is a kind of hair very fine and twisted in all directions, or finally in down. The Rhinoceros has an azygos solid horn, formed of agglutinated fibres like whalebone, growing upon the nose. Ruminants, except the Camelidse, have a pair of frontal horns, either solid and permanent like the Giraffe, or solid and annually deciduous as the deer-tribe, or finally hollow and permanent. The solid horns are bony processes from the frontal bone, covered by 54 SYLLABUS, ETC. a fine velvety skin, which, in the deciduous variety, dies at a certain period of the year, leaving the horns or antlers bare, when they too soon die, and drop off to be replaced by a new set, larger and with more branches than the old. The hollow horns are hollow cones of horny tissue implanted upon bony prominences filled with air cells that communicate with the nose. Great expansion of the neural arches of all the cranial vertebrae, especially the parietal, for the protection of the progressively developing brain. In most of the class an additional cranial element is gained by the expan- sion of the distal end of the diverging appendage from the supe- rior maxillary bone, namely, the squamosal bone. Tympanal bone displaced by the intervention of the squamosal and reduced in size; mandibular arch (lower jaw) coalesced into one piece on each side, (these often united at the symphisis) always articulates with the tem- poral bone by an undivided condyle; occiput articulates with atlas bjtivo condyles; cervical vertebrae always seven in number, except in the Pangolin, which has only six, and the three-toed sloth which has eight or nine. Coracoid bone, so conspicuous an element of the scapular arch in the oviparous vertebrates is not, in most mam- mals, sufficiently developed to reach the sternum; clavicles more frequently connect the scapula with the sternum, but they are often wanting, as in horses and most mammals which use the anterior limbs exclusively for station and progression by moving only forwards and backwards. Digestive apparatus.—Peculiar straining apparatus of the whalebone-whale (Bala?na mysticetus). Numerous small, conical reptilian teeth of the porpoise, dolphin, armadillo, &c. In mam- malian teeth, except those which grow from a persistent pulp (as the tusks of the elephant, the chisels of the Rodentia, and the molars of the Edentata) the dental cavity is closed in at its lower part, and the base of the tooth is prolonged into a fang, which is implanted in a proper socket formed by a projection of the bony substance of the jaw that grows up to invest it; this is peculiar to this class, and further, no known vertebrate but a mammal has teeth implanted by bifid fangs. Fleshy lips, tongue, salivary glands, velum pendulum palati, epiglottis, muscular pharynx, and oesopha- gus. Stomach either (1) simple, or (2) complex, as in kangaroo, &c.; or (3) compound, as in Ruminants. Small and large intestine. Gall bladder sometimes wanting, as in the horse, &c. Heart double. Portal circulation. Respiration single. Special pro- visions for the safety of aquatic mammalia, who remain submerged for some time. Blowing apparatus of Cetaceans. The skin of all quadrupeds contains innumerable sebaceous fol- licles, furnishing an unctuous matter for lubrifying the skin. Sometimes a number are aggregated together so as to form secret- ing pouches, as just below the orbit in stags, furnishing a secretion commonly called the " Stag's tears." Often such pouches furnish a highly odorous material, especially in the vicinity of the organs of generation, as the castor glands of the Beaver, the musk gland SYLLABUS, ETC. 55 of the musk Deer, and the anal glands of the Carnivora. which have an intolerable stench in the Skunk and Polecat. Genital apparatus among the Placental orders does not deviate largely from the human type; and that of the Implacentalia has already been noticed. The peculiarities of the kidneys, of the absorbent system of vessels and glands, of the brain and organs of sense of Mammalia and other vertebrates, will be noticed in connection with the phy- siology of these organs. ON THE OBJECTS AND PRINCIPLES OF ZOOLOGICAL CLASSIFICATIONS. 114. Why this topic was reserved for this point in the course of lectures. Immense number of animal species, each with its double name generic and specific. Definition of a natural classi- fication. Relation of analogy ; relation of affinity or homology, which is more fruitful as the basis of a natural classification. Illus- tration from the comparison of Whales with Fishes on the one hand, with which they are connected by relations of analogy, and with quadrupeds on the other, with whom they differ in general appearance and habits, but agree in all the important features on which the class Mammalia is founded. Hence to class whales with man and beasts is a far more natural arrangement than that which the unlearned make from contemplating their fish- like habits. So, too, Bats are unnaturally classed with Birds. their real place being with other mammals. An artificial classi- fication is one which does not necessarily indicate the natural affinities of the objects classified, as the Sexual System in Botany. Possible advantages of such a classification, if skilfully constructed. Characteristics of a natural classification. Advan- tage to be derived from having some single and easily discovered external character, even though it be artificial, as an index or ex- ponent of a group of natural characters with which it is found to coincide. Examples, feathers, a sign of all those natural characters which are indicated by the term Bird; hair, significant of mamma- lian organization, &c. &c. 115. The entire collection of animals called the Animal King- dom. The primary divisions, termed sub-kingdoms, have each, in addition to the characters which belong to the whole kingdom, some other features common to all its own members, but not pos- sessed by other sub-kingdoms. The zoological sub-kingdoms, founded on the varying types of nervous system, which seem to govern the whole organization, are exceedingly natural, if Ave except only the Protozoan, which is founded on negative charac- ters. The primary divisions of a sub-kingdom termed Classes. Most of the animal classes are natural groups, as for example, the Vertebrate classes, Mammalia, Aves, Pisces, and even Reptilia, 56 SYLLABUS, ETC. if we exclude the Batrachians, and raise them to the rank of a separate class, Amphibia. But there are some instances of classes founded on artificial characters, as Entozoa, a group which really includes animals belonging to three different sub-kingdoms. The immediate sub-division of classes termed Orders, which are more frequently founded on some single character, and therefore less natural than either the higher or the lower groups. Orders are sub- divided into Tribes or Families ; and the animals included in such a group are marked by a natural family likeness, as for example, the Canidae, the Dog tribe or family, which includes the Dog, the Wolf, the Fox, and the Jackal; and the Felidoe, including the Cat, Lion, Tiger, Leopard, &c. Families include a number of Genera, that is, collections of animals resembling each other in all the im- portant features of their organization; and finally, a genus includes, or may include a large number of species, which is the term applied to all those individuals which are constantly marked by the same characters with only such slight occasional variations as are compatible with the idea of a common parentage. Such a group is altogether natural therefore. Any constant or invariable difference, however slight, is yet adequate to indicate a difference of species, a necessary consequence of the law of resemblance be- tween parent and offspring. To go over the same ground in the reverse order, we observe that nearly allied species, that is, species recognized as different by some constant point of distinction, which however is intrinsically unimportant, while the points of resem- blance are numerous, and have respect to all the important fea- tures of organization, are grouped together as one Genus. In the same manner closely allied genera are ranked as one family or tribe. Families, resembling each other in natural, or even in cer- tain artificial characters, are placed in the same order; allied orders make a class, and classes having a certain degree and kind of affinity, are grouped together as a sub-kingdom. " Thus as we pass from species to genera, from genera to families, from families to orders and from orders to classes, the characters of agreement become fewer and fewer ; whilst those of difference manifest them- selves more and more strongly. And when we arrive at classes, we may generally say that the points of difference are stronger than those of agreement." Typical representatives of any natural group of animals. Genus Felis, a typical genus of the family Felidae, the latter being a typical family of the order Carnivora; the order Insessores, a type of the class Aves. So Annelidans and Myriapods may be regarded as retaining more of the dis- tinctive characters of the sub-kingdom Articulata, than either the Arachnidans, Crustaceans or Insects, all of which in their higher forms diverge in different directions and nearly equal degrees from the common fundamental type. Aberrant groups. Osculant groups. Examples: Sub-class Cirrhopoda are aberrant Crusta- ceans, being osculant between the typical Crustaceans and Aceph- alous Mollusks. The class Bryozoa osculant between the mol- SYLLABUS, ETC. 57 luscan sub-kingdom to which it truly belongs, and the Radiate class Polypifera, to which it bears some points of resemblance. ON SPECIES AND VARIETIES IN THE ANIMAL KINGDOM. 116. Species defined by Cuvier to be the " collection of all the beings descended the one from the other, or from common parents, and of those which bear as close a resemblance to these as they bear to each other ;" by others to be " a race of animals or plants marked by any peculiar character which has always been constant and undeviating." These are substantially the same, the one as- serting what is implied in the other. May be deduced from the law of resemblance between parent and offspring, upon which depends the possibility of identifying species. Flexibility of this law within certain limits, under the operation of external influences; the results of the partial modification thus induced being then per- petuated under the operation of the original law. Illustrations derived from the transmission throughout a large family of pecu- liar traits originating in a given individual ancestor, when a pe- culiarity thus acquired becomes permanent in a group of individuals breeding among themselves. Such a group is designated a variety. A variety is thus a group of animals marked by the permanent reproduction of some distinctive feature, which feature however, may be shown to have been acquired in superaddition to, or as a modification of the characters of the species to which the animal truly belongs. 117. Tests of unity of species in the case of groups of animals characterized by such permanent peculiarities as to constitute the distinctions of varieties, (a) Historical evidence. Varieties of the hog, of the horse, of the dog, and of horned cattle now found in America, and known to have issued from domestic breeds intro- duced by Columbus and his followers. Notice of the kind and extent of diversity exhibited by these varieties as compared with the original stock, (1) as to structural characters; (2) as to physi- ological and psychological qualities. Habits acquired by certain animals and then transmitted to their offspring, which thus inherit traits originally acquired by the parent. (b) Value of structural differences in the discrimination of spe- cies. The peculiarities which mark a variety being liable to dis- appear on the removal of the causes which originally produced them, there are generally found intermediate gradations tending to connect the most extreme varieties with each other, and with the typical characters of the original and common stock. On this ground, all the varieties of dogs are assumed to belong to one spe- cies, since it is impossible to mark off the boundaries of more than one species, by reason of the intermediate grades which connect the extreme varieties with each other and with the wild stock whence all have, doubtless, sprung. On the other hand a differ- 58 SYLLABUS, ETC. ence of species is indicated " when the characters which separate two races are transmitted with complete uniformity, when there are no intermediate gradations tending to connect them, and when no such tendency to variation has manifested itself in either race, as shall make it probable, or, at any rate, possible, that their dif- ferences may be attributed to some unusual divergence in the cha- racters of the offspring from those of the parents." (Carpenter— " Varieties of Mankind." (c) Value of physiological and psycho- logical peculiarities in the discrimination of species—often a surer criterion than structural characters. Sterility of hybrids rendering impossible the existence of a hybrid species. Constant and uni- form agreement among animals of the same species, but of diver- sified varieties, as to the great laws of the vital functions, such as those " which express the periods and duration of life, the economy of the sexes, and the phenomena of parturition and reproduction." Decided differences in regard to the same peculiarities among races which, though very nearly resembling each other are yet speci- fically distinct. Every species characterized by the possession of instincts and propensities peculiar to itself, so that the instincts of different, though nearly allied species may differ remarkably, while those of different varieties of the same species, notwithstanding very strong- ly marked diversities of physical structure, are fundamentally the same. 118. Application of these principles to the case of the Races of Mankind. Setting aside the historical evidence, on account of the doubts entertained by some naturalists as to the correct inter- pretation of the teachings of Scripture on this point, (although the statements of the inspired writers appear to be sufficiently explicit, and in accordance with the inductions of science,) it is to be observed that the peculiarities which distinguish the several races of mankind, run into each other by changes so numerous and gradual as to make it utterly impossible to determine the boundaries of more than one species. No two naturalists can agree as to the number and characteristics of the different races. Taking the Western Europeans and their American descendants, as one extreme, and the Bushmen of Southern Africa as the other, we find interme- diate grades which connect these very remote extremes by gradual transitions. Again, within the limits of a single variety there oc- casionally appear as an accidental anomaly, traits of conforma- tion identical with those which distinguish a different variety. And finally, on this head, an entire race marked by certain pecu- liar traits of conformation have, on changing their mode of life, after some centuries lost those traits and acquired others. Three general types, into which the varieties of the human race fall, as regards their physical characteristics. (1) Prognathous type of savage and hunting tribes ; (2) Type of the Pyramidal skull, found in the nomadic and pastoral tribes ; (8) Type of the oval or ellip- tical skull, belonging to those races that have been subjected to SYLLABUS, ETC. 59 the influences of civilization. " Turks of Europe now exhibiting the oval skull, are known to be descendants of the Turks of mid- dle Asia, who exhibited the pyramidal form. So, too, the Magyars of Hungary." " The very fact of the extensive dispersion of a race, and of its existence under a great variety of external con- ditions implies a marked capacity for variation ; since without such capacity the race could not continue to flourish." (Carpenter, loc. cit.) So far, then, as structural peculiarities are concerned, they lead to the doctrine of the specific unity of the several races of mankind. " The conformity among these races as to physio- logical phenomena, furnishes a yet stronger argument; for in- stance, the power of indefinite cross breeding, often with the re- sult of improving the parent stock. The average duration of life un- der the same circumstances, is the same for all; the extremes of lon- gevity the same ; the epoch of the first and last menstruation and the length of the intermenstrual interval, the duration of preg- nancy, the periods of dentition, &c, &c, all point to the con- clusion of the unity of the human species, while they establish a specific difference between man and the most anthropoid apes. Again, the correspondence between the different races of mankind in j. ., respect to physical endowments, leads to the same results, all having '. the same intuitive convictions, the same primary faculties of mind, <■( (. the same kind of susceptibility to improvement, though, perhaps, not always equal in degree, and the same feelings of fear or hope in reference to a future state of existence beyond the grave. (Prichard.) 119. In accordance wdth the terms of the definition given in § 116, it has commonly been held that all individuals belonging to the same species must have sprung from one original pair. Thus Latham says, " a multiplicity of protoplasts (original parents) for a single species is a contradiction in terms. If two or more such individuals or pairs, as like as the two Dromios, were the same protoplasts to several classes of organized beings (the present members being as like each other as their ancestors were,) the phenomenon would be the existence in nature of more than one undistinguishable species, not the existence of more than one protoplast to a single species." (Latham—Races of Mankind.) Notice of recent attempts to draw a distinction between unity of spe- cies and community of origin, and to show that the several species were originally created in the same relative numbers in which they now exist,—that all the original individuals of the same species pos- sessed the same essential nature, modified, however, in accordance with the special conditions in which each was destined to exist. No- tice of the argument of Agassiz, the leading supporter of this novel doctrine, in supporting which he very eloquently demonstrates the specific unity of the races. Opposite conclusions of eminent Zoologists and Geologists. Thus, Prof. E. Forbes rejects the whole hypothesis of the radiation of species from separate centres, and avers "that the peculiarities in the geographical distribution 60 SYLLABUS, ETC. of existing species are quite reconcileable with the idea of migra- tion from single centres, and that, generally speaking, they lead necessarily to that idea." (Carpenter, loc. cit.) So, too, Sir. C. Lyell declares, that "there appears to be no sound objection to the doctrine that all the leading varieties of the human family have originally sprung from a single pair." 120. Tabular view of the leading divisions of the Animal Kingdom. A. Sub-kingdom Protozoa. No positive characteristics, except such as belong to all animals. The distinctive character is the negative one of the absence of a nervous sys- tem ; no special vascular system; no localized respiratory apparatus; gen- ital system diffused, &c, &c. / 1. Class. Polygastrica. Infusorial, mi- croscopic. Supposed to be characterized by multiple stomachs ; but this character is doubtful, and the class is probably not natural. 2. Class. Rhizopoda. Mere organic cells filled with granular semi-fluid matter, ca- pable of altering their shape by projecting the integuments in various directions. Most species loricated, with root-like feet projecting through pores in the shell. 3. Class. Porifera. Motionless andun- irritable ; flesh supported on a fibro-cor- neous skeleton, covered with pores and vents. B. Sub-kindgom Radiata or Cy- cloneura, characterized by the pre- sence of a nervous sj-stem which, when discernible, consists of nervous threads arranged in a circular form around the mouth with radiated branches. In some the nerves have not been discerned, (Acrita,) but their actions imply the existence of such organs. Circular symmetry of the body, or of the parts around the mouth. Alimentary canal with its own special walls in all except the Hydroid Polypi. Blood-vessels first appear in this group, at first as mere continuations of the alimentary pas- sages (Acalepha), but soon as dis- tinct organs with pulsatile walls in some places (Echinodermata), but en- tirely wanting in most Polypifera. Respiratory apparatus also gradually evolved, being localized in the Holo- thuridans as an arborescent set of tubes. Generative apparatus, very simple and of the monoecious type in Polypi, rises to the dioecious type in the other two classes. Alternate generation. / 1. Class. Polypifera. Soft, inarticulate, acrite. Of saccular form with orifice sur- rounded by prehensile tentacula. Some- times single ; more frequently composite, with a common polypary partly fleshy and partly horny or stony. Two orders, Hy- droida and Actinoida. 2. Class. Acalepho?. Mostly acrite. Of various shapes ; of glassy transparency and gossamer texture, with an enormous rela- tive amount of water ; stinging property; phosphorescence. Four orders. Pulmo- grada. Ciliograda. Cirrhigrada and Phy- sograda. 3. Class. Echinodermata, with a dis- tinctly radiate nervous system ; a contrac- tile skin having, commonly, calcareous plates imbedded in it. Many have prickly spines; many also have tubular cirrhi for locomotion ; but the class is naturally cha- racterized by its advanced grade of organi- zation as compared with the other radiate classes, having a distinct vascular system and a progressive developement of a dis- tinct respiratory apparatus, &c. &c. Six existing orders, as Crinoidea, Ophiurida, Asteriada, Echinida, Holohurida and Sipun- \ culida. SYLLABUS, ETC. 61 C. Sub-kingdom. Mollusca or Hetero-gangliata. Hetero-gang- gliate nervous system. Body asym- metrical, soft and without dermo- skeleton, having only a muscular skin called "Pallium" or mantle. Whole body often inclosed in a testa or calcareous shell, univalve, bivalve, or multivalve. Preponderating deve- lopment of nutritive apparatus and great deficiency, in most cases, of the powers of animal life. Long, convoluted intestinal tube ; large and active liver. Heart, found in all but the Bryozoa, systemic except in Tunicata, where it is alternately sys- temic and pulmonic. Distinct respi- ratory apparatus in all except the class Bryozoa, and in all except the Ascidian family of the Tunicata it opens at or near the anus. Multiplication by budding in the lower classes, Bryozoa and Tunicata. Hermaphrodism quite common a- mong Gasteropods. All the higher classes organized on the Dioecious type. D. Sub-kingdom. Articulata. Homogangliata, or Diploneura. Animals which exhibit the Homo- gangliate type of nervous system; that is a nervous system consisting mainly of separate ganglia, which are similarly arranged in the different segments of the body. In general the body is composed of similar seg- ments, succeeding each other longitu- dinally and by their connection pre- senting the jointed appearance from which the most common name (Arti- culata) of the sub-kingdom is deriv- ed. In the more typical forms there is a double ganglion in each seg- ment, the first or cephalic segment having its ganglion above the oeso- phagus, while the ganglia of all the succeeding segments are ventral, or below the alimentary canal. In the lower forms the ventral chain of ganglia is replaced by a double nerv- ous cord without ganglia, and hence the use of the term Diploneura, as one of the synonymes of the sub- kingdom. f 1. Class. Bryozoa. Zoophytic mol- lusks ; microscopic; no heart; no special respiratory system. Single nervous gang- lion. 2. Class. Tunicata. Low molluscans inclosed in a leathery tunic with two ori- fices. Single nervous ganglion. Heart with one cavity. Respiratory chamber. 3. Class. Palliobranchiata or Brachio- poda. Bivalve mollusks with the whole mantle arranged for respiration. 4. Class. Lamellibranchiata. Bivalves with respiratory organs in the form of four lamellae between the two lobes of the mantle. One or two muscles; three or more ganglia. All the foregoing are ace- phalous. 5. Gasteropoda. Under surface of the belly, or a part of it developed into a disk adapted for sluggish locomotion. Distinct head bearing tentacula, eyes, oral appara- tus, &c. Supra (Esophageal ganglion or brain; other scattered ganglia ; one order breathing air by means of pulmonary cham- bers, others breathing water by localized branchiae ; most inhabit univalve shells. 6. Pteropoda. With lateral alar appen- dages for swimming. 1. Cephalopoda. Mouth in the centre of a disk, surrounded by large fleshy arms. Very large brain protected, in some species, by a rudimental cranial cartilage. 1. Class. Entozoa, not a natural group ; including the members of at least three classes belonging to as many different sub- kingdoms, but all exhibiting a tendency to the articulate type in which the highest of them culminate. These form the Nematoid order, characterized by diploneurose grade of Homogangliate type. Straight alimen- tary tube ; a few longitudinal blood-ves- sels ; dioecious type of genital apparatus ; very long and convoluted ovaries; vulva in front of the middle of the body. 2. Rotifera. Microscopic and infusorial articulates with one or more rota; or fleshy lobes being vibratile cilia. / 3. Annelida or Anncllata. Soft-skinned vermiform articulates either entirely apo- dal (Leech), or with only rudimental legs in the form of unjointed setae ; nonparasi- tic ; elaborate development of vascular system with arteries, veins and multiple hearts, (i. e. portions of the arteries dilated and pulsatile); ventral chain of ganglia. The absence of these characters in the non parasitic Planariae causes them to be ranked with Entozoa, leaving the Annelida a natural class. 4. Class. Myriapoda. Articulates of numerous similar segments, all of which, except the two terminal ones, bear one or two pairs of feeble but jointed legs. ^.Breathe air by tracheae. 62 SYLLABUS, ExC. Sub-kingdom—Articulata. tinued.) (Con- Some are without legs, (vermi- form.) Some have locomotive appen- dages to all the segments except the two terminal ones, (myriapoda) others have such appendages to special seg- ments only. Mouth sometimes suctorial, and more or less circular, but when armed with mandibles, maxillae, &c, these are always at the sides and move laterally. Every variety of alimentary, circulatory and respira- tory apparatus found in the different classes of this sub-kingdom. The dioecious type of generative appara- tus prevails, but there are instances of hermaphrodism in the lower classes. Articulate classes. (Continued.) 5th class.—Insecta. Body in the embryo state consisting of thirteen segments, which subsequently in most species become more or less consolidated into three regions, namely, head consisting of one segment, thorax of three, and abdomen of nine. In a few there are fourteen, of which two form the head, (Hymenoptera and Diptera.) Three pairs of legs attached to thorax; most have two pairs of wings; one order has only one pair, and some orders are en- tirely apterous. Tracheary respiration. Vasiform heart or dorsal vessel. Blood vessels mostly lacunar passages. Salivary, biliary, urinary, ovarian and testicular or- gans, all tubular; generative organs always dioecious. Most undergo metamorphosis, passing through the several conditions of Larva, Pupa and Imago. 6th class.—Arachnida. Air-breathing articulates with four pairs of legs. Head and thorax united into cephalo-thorax; no antennae; but very large maxillary palpi which appear like a fifth pair of legs, espe- cially in the Scorpionidw, or Pedipalpi. Two orders: Pulmonaria, breathing by air chambers, and having a well developed vascular system ; and Trachearia, breathing by ramified tracheae. 7th class.—Crustacea. Embracing all water-breathing articulates with jointed locomotive members, and divided into four sub-classes. (1) C. Malacostraca, the soft shelled or ordinary crustaceans, contain- ing the familiar genera, crabs, lobsters, &c. (2) C. Entomostraca, minute crustaceans of stagnant water, often enclosed in bivalve shells. (3) C. Suctoria. External parasites; aberrant; osculant between true Crusta- ceans and Entozoa. (4) C. Cirrhopoda. Soft, acephalous, with cirrhiform arms; muscular and mantle-like skin ; testaceous ; very aber- rant, osculating with molluscans, but yet distinctly articulate in the arrangement of the nervous system, and in lateral sym- metry with a faint indication of segmental structure. In the larval condition it is free, and resembles an entomostracan. When mature, it is enclosed in a shell, and fixed either by the fusion of its shell to the rock, (Sessile order) or by means of a long con- tractile pedicle. (Pedunculated order.) SYLLABUS, ETC. 63 E. Sub-kingdom—Vertebrata, Spi- ni-cerebrata or Myelbncephala. Animals with a cerebro-spinal axis; that is, a dorsal column of ganglionic matter in one continuous cord, swell- ing out at the anterior end into a multiple mass called the brain ; the whole being lodged in and protected by a jointed bony case, composed of a series of annular segments called . vertebrae. Generally five senses. } Blood always red, a character due to the blood disks which are peculiar to the members of this sub-kingdom. Nutritive apparatus well developed in correspondence with the rapid waste of the active nervous apparatus, and exhibiting spleen, pancreas, portal system and absorbent system, in ad- dition to the organs found among the higher invertebrata. Respiratory, circulatory and generative apparatus variable in the different classes. 1st. class.—Pisces. Cold blooded, breath- ing water by localized gills; circulation single and pulmonic; body generally cov- ered by scales: locomotion effected chiefly by lateral flexions of the trunk and tail. Generation oviparous, the ova being fertil- ized after extrusion in most cases. 2d. class.—Amphibia. Cold blooded vertebrates, which when first hatched have the anatomical and physiological characters of fishes, &c. Subsequently undergo a metamorphosis, as the result of which they acquire lungs for breathing air and other reptilian characters. Skin naked. Generation oviparous. 3d class.—Reptilia. Cold blooded; breath- ing air by means of lungs. Circulation imperfectly double, the two kinds of blood being mixed in a single ventricle, or shortly after issuing from two ventricles. Body covered with scales, or else with bony scutes. Generation oviparous. Three orders presenting as many different types of reptilian development, namely, Chelonia, Ophidia, and Sauria. 4th class.—A ves. Warm blooded, breath- ing air by lungs and disseminated sinuses, making a double respiration. Circulation completely double, or heart with four cavities. Body covered with feathers ; an- terior extremities formed into wings. Gene- ration oviparous. 5th class.—Mammalia. Warm blooded. Single respiration by localized but very perfect lungs. Circulation as in birds. Body covered with hairs ; anterior extre- mities organized for station or for prehen- sion, very rarely for flight, (Cheiroptera— Bats.) Generation viviparous, or, among the Implacentalia ovoviviparous. 64 SYLLABUS, ETC. 7 ■■'-' SPECIAL PHYSIOLOGY. CLASSIFICATION OF THE FUNCTIONS OF MAN. 121. The special functions are subservient to one of two pur- poses, the well-being of the individual or the perpetuation of the rac e. Hence the basis of a primary division into two great sections. (I.) Those which have reference to the life of the individual be- ing ; and (II.) Those which look to the propagation of the species. The first of these sections sub-divided into two subordinate classes, viz.: (1) Those which are subservient to the development, growth and maintenance of the fabric, and which are therefore termed nutritive or vegetative functions, or the Functions of Organic Life; and (2) those which serve to establish relations between the individual and the surrounding world, or Functions of Relation which, being peculiar to animals, are also called Functions of Animal Life. The second great section, embracing the Func- tions of Reproduction, as executed by man and other higher animals, both vertebrate and invertebrate, will admit of a similar binary sub-division ; but inasmuch as the essential part of these functions is exclusively organic, it will be convenient to class them with the nutritive functions pertaining to individual life under the general term, functions of organic life. A.—functions of organic life. I. Functions of Reproduction or Generation. 122. These consist (1) of acts executed by parents of different sexes, and which, although in man and the higher animals gene- rally they involve incidentally the co-operation of animal func- tions, are yet organic in their essential nature, as they are ex- clusively so in lower animals and in all plants. (2) Of a series of intra-oval and intra-uterine developments constitutinc the evo- lution of the embryo. II. Functions of Nutrition or Assimilation. These consist in a series of acts whereby crude alimentary matter is converted into pure arterial blood, and the several parts of the fabric are developed and maintained at the expense of the blood, with certain incidental phenomena important to the in- SYLLABUS, ETC. 65 tegrityof the system. (1) Digestion; (2) Chylosis; (?>) Hsema- tosis ; (4) Respiration as a means of the ingestion of oxygen ; (5) Circulation; (6) Secretion; (1) Nutrition; (8) Respiration as a means of excretingcarbonic a/rid; (9) Urinary, Biliary, Cutane- ous and other excretions ; (10) Calorification. B.—FUNCTIONS OF RELATION, OR OF ANIMAL LIFE. These include the functions of the nervous system and the actions of those muscles which in respondence to nervous stimu- lation effect the different movements of the trunk and its appen- dages. By the instrumentality of these acts even in the lowest grade of their manifestation, the simplest animals, save only those unconscious organisms called Protozoa, are brought into re- lation with the external world in two ways, (1) by receiving and feeling impressions of external agents on the organs of sense (sensorialfaculty), and (2) by reacting on external objects by means of the muscles and bones, under the stimulus of a nervous force generated by the will (volitional exercise of the motorial faculty), or else excited by a prior action of an impressed nerve indepen- dently of either consciousness or volition. (Physico-reflex ex- citement of the motorial faculty.) In this connection are to be noticed the phenomena of animal instinct, and the connection be- tween the mind and the brain as its instrument. FUNCTIONS OF ORGANIC LIFE. I. FUNCTIONS OF GENERATION. 123. Reasons for commencing the course with the consideration of this subject. Statement of certain general laws of genera- tion. (1) Omne vivum ex ovo—proof of this law. (2) Law of resemblance between parent and offspring. Qualifications of this law. (a) Admissibility of variations, so as to form varieties within the limits of species, when the variations are inherited and trans- mitted to a group of individuals which are isolated from those of the same species that do not exhibit the same peculiarities, (b) The phenomenon of "alternate generation" another apparent exception. Statement of examples and true interpretation of the phenomena. (3) Susceptibility of multiplication by budding (gemmiparous reproduction) and by spontaneous division (fissiparous), exhibited by certain low organisms. But in such cases it would seem that developmental power is expended, and the race would be annihi- lated after a time, unless this power were renewed in some other way, as (4) True Generation, which seems always to require the 66 SYLLABUS, ETC. union of the contents of two cells, the female or germ cell,^ and the male or sperm cell, whether these be found in the same indi- vidual (Monoecious, Hermaphrodite, or Androgynous type), or in different individuals (Dioecious type). Three principal modes of effecting this union observed in the vegetable kingdom, but only one in the animal world. 124. Action of the Female in Generation.—Essential element of the female generative apparatus a cell of peculiar endowments, the " Germ Cell." Diffusion of such cells as also of the male or " Sperm Cells," in a few of the lowest animals, with whom mul- tiplication by budding or by division may present the conditions of true generation. Germ cell, under the name of germinal vesicle, with its germinal spot in its centre, is found in the centre of a mass of oily and albuminous matter, called vitellus (yolk), inclosed in a thick membrane, the membrana vitelli or zona pel- lucida, the whole structure being termed ovule, or when fertilized, ovum. Ovarium, any special arrangement of tissues for the de- velopment of ova. Oviduct, tube for extrusion of mature ova. TABULAR VIEW OF THE VARIETIES OF OVARIES. 125. (1) No true ovarium, ova being developed throughout the general parenchyma, as in the Porifera or Sponge tribe. (2) Ova developed in a mass in particular localities, but without any special arrangement of the tissues; as at the base of the body in the genus Hydra, the sperm cells being developed near the base of the tentacula. (3) Ova developed in the substance of a simple membrane, not arranged into a tube or sac, and when mature, being discharged first into the general peritoneal cavity, whence they issue by various means ; as in the Actiniform Polypi, Eels, Lampreys, Frogs, $c. (4) Ova developed in the substance of a membrane forming the walls of cylindrical tubes, into which the ova are received when mature, by a rupture of the enveloping membrane. Echinoder- mata and most Entozoa, §c. (5) Similar in form to the last; but the tubes are very dilatable, and when distended with ripe ova are large sacs. Insects, Arach- nidans, Crustaceans, Osseous Fishes, §c, §c. (6) Similar to the last, except that the ova are developed in masses suspended by narrow pedicles to the walls of the sac, like bunches of grapes. Cephalopod Mollusks. (7) Ova in various stages of maturity developed in ovisacs in racemose branches without any tube, being merely bound down by the peritoneum and a little areolar tissue. Reptiles and Birds. (8) Ova developed in ovisacs which are lodged in the meshes of a fibro-areolar stroma, and the whole covered by peritoneum. Mammals. SYLLABUS, ETC. 67 VARIETIES OF OVIDUCTS. 126. The three first named varieties of ovaria require no oviduct, if we except only the special arrangement in frogs, described below (number 2); the ova in other cases being voided directly from the place of original development, or after being discharged into the peritoneal cavity they escape by slits at or near the anus. (1) Oviduct a simple continuation of the tubular or saccular ovaria, with, in some cases, a special dilatation for the temporary detention of the ova, in order to. receive a mucus covering, or to be fecundated by means of sperm previously received into such spermotheca. This variety of oviduct is found in connection with varieties (4), (5), and (6) of ovaria. (2) Special oviduct with trumpet-shaped orifice at some distance from the ovaria, so that the ova have to pass through the interve- ning space in the peritoneal cavity; oviduct opening into cloaca. Frogs. (3) Similar to the last, except that the dilated orifice of the oviduct lies near the ovarium, and applies itself around the mature ovum when the latter is about to be discharged. Reptiles and Birds. (4) Somewhat similar to the last in its relation with the ovarium, but the two oviducts now called fallopian tubes present dilatations in their course, such as one or two uterine cavities, in which the ovum is retained in order to establish a secondary connection with the maternal system, and a vaginal canal or organ of copulation. Mammals. 127. Structure of the ovarian or unfertilized ovum in oviparous vertebrates. Large amount of vitellus, of which a small portion near the germinal vesicle is lighter and less opake (Discus Vitel- linus) and probably corresponds with the whole vitellus of the ma- malian ovum. Ovisac. " White" of,the egg; membranaputaminis ; shell. 128. Characters of the mammalian ovule. Graafian vesicle of two layers, the external being the condensed vascular stroma, the internal a non-vascular ovisac; membrana granulosa; Discus Proligerus. Dimensions of human ovum. Zona Pellucida or vitelline membrane ; vitellus ; germinal vesicle and germinal spot. Development of the several constituents of the ovum. Changes in the ovum and ovarium preparatory to fecundation. Sympathetic actions of the uterus. Phenomena of "heat" in brutes, and of menstruation in the human female. Analogies between these phe- nomena; their dependence on the maturation and discharge of unfertilized ova and other correlative ovarian changes. Difference between the corpus luteum of the virgin and that belonging to the condition of pregnancy. 129. Male Sexual Functions.—The only essential part of a 68 SYLLABUS, ETC. male apparatus of generation is an organ for the development of the male or sperm cell, the union of which with the germ cell is an indispensable condition for the formation of a body endowed with developmental capacity; accordingly, in very low animal organisms the male apparatus, as simple as that of the female, consists in a mass of sperm cells developed in the general paren- chyma and escaping like any other excretion. But in higher beings, parts are superadded for conveying outwardly the sperm cells, the product of the secretion of particular glands called Testes ; and in very many animals for injecting this product into the vaginal passage of the female by means of an erectile organ of intromission. General view of the whole apparatus in man; sensible characters of the seminal liquid; microscopic characters and development of spermatozoa. Their true nature in relation to the process of fecundation. Reasons for believing that fecun- dation is accomplished in the outer part of the fallopian tube rather than in the ovary or in the uterus. 130. Development of the Embryo.—Changes in the ovum immediately subsequent to a fecundating copulation and while the ovum is yet in the fallopian tube. Changes of the ovum within the uterus, divided into three stages. (1) Changes prior to the forma- tion of the omphalo-mesenteric vessels. (2) Development of the allantois as a temporary organ of aeration of the blood of the embryo, and representing the only vascular connexion which is established between the maternal system and the embryos of non- placental mammalia. (3) Changes connected with and subsequent to the development of the placenta. SUMMARY RECAPITULATION OF THE PHYSIOLOGY OF GENERATION. 131. A. Assignment of organs in each of the sexes, with a speci- fication of the uses of each part of the complicated apparatus in the human species. B. Explanation of the function ; (a) to assign proximate cause ; any and every formative or developmental ope- ration in a living organism involves the necessity of a threefold condition ; (1) a germ or body which is to undergo development; (2) alimentary or nutritive materials at the expense of which the fabric is built up ; and (3) certain dynamical stimuli, such as a proper temperature and degree of moisture, &c, &c. But the germ must be endowed with developmental power; and three theories have been maintained with regard to the origin of such germinal capacity; some supposing that it resides inherently in the germ-cell, and only requires to be stimulated by the seminal liquid, which is thus held to act like heat or any other mere dynamical stimulus (ovarists); others asserting that the developmental capacity resides exclusively in the sperm-cell; and that the germ-cell as well as its vitellus is to be regarded as a mass of peculiar nutriment that also SYLLABUS, ETC. 69 acts as a dynamical stimulus, (Animalculists); while a third and now generally accepted theory termed Epigenesis, maintains that neither parent furnishes a complete germ, but that the latter is formed or generated by the conjugation of elements derived from both. ^ This appears to be demonstrated by the phenomena of Hybridity. (b) To assign exciting causes. The developmental capacity with which a duly formed germ is endowed by the act of conjugation between the germ and sperm-cell, is not manifested as & force, that is, the developmental changes do not take place, except under certain favoring conditions, which are therefore termed stimuli or exciting causes, of which heat and oxygen are especially neces- sary. In viviparous animals, these, as well as nutritive materials, are abundantly supplied in the maternal system and immediately after fecundation. In warm blooded oviparous vertebrates, a small amount of change takes place in the maternal system, but the ova being soon extruded, the process is arrested for want of the requisite heat until this is subsequently applied either artificially or by natural incubation. In cold blooded ovipara the animal heat of the parent is seldom sufficient and the ova have to be subjected to the influence of solar heat more or less directly. (c) Laws.—In addition to the laws already stated (§ 123), we note the following, which apply to the human species. (1) Ova be- come mature and are discharged periodically from the ovary, inde- pendently of fecundation and coinciding with the catamenia. (2) Fecundation cannot, it is probable, occur in the ovary nor in the uterus, but must be accomplished in the fallopian tube. (3) There is an intermenstrual epoch at which fecundation is almost or quite impossible, namely, ten or twelve days after one menstrual period to within a few days, perhaps, of the next. (4) Fecunda- tion is most likely to occur at or near a menstrual period. (d) Final cause—to perpetuate the species. (e) Local and general sympathies. Morning sickness in the earlier stages of pregnancy ; areola around the nipple; kiestine in the urine; and certain later phenomena, the consideration of which belongs to the subject of Practical Midwifery. II. NUTRITIVE OR VEGETATIVE FUNCTIONS. 132. Necessity for the execution of this class of functions, (1) from the instability of the chemical compounds which constitute the proximate components of the tissues, by reason of which they are constantly undergoing decomposition, and require to be replaced by new material. (2) The more rapid and abundant waste which is one of the conditions of the actions of the organs of animal life, by reason of which no nervous or muscular fibre is equally fit for two successive actions unless it have regained in 70 SYLLABUS, ETC. the interval what it lost by the first action. The raw material for this restoration is obtained from without in the form of food, and has to undergo a series of changes before it can be used for such purposes ; and these several changes are the results of the several nutritive operations. These are (1) Digestion ; (2) Chylosis ; (3) Haematosis; (4) Respiration as a means of absorbing oxygen ; (5) Circulation ; (6) Nutrition proper ; (7) Secretion ; (8) Respiration as a means of excreting carbonic acid ; (9) other purifying excre- tions ; (10) Calorification. FUNCTION OF DIGESTION. 133. Definition.—Enumeration of the subordinate acts, namely, (1) Prehension; (2) Mastication ; (3) Insalivation ; (4) Degluti- tion ; (5) Chymification or action of the stomach; (6) Intestinal digestion or action of small intestine, and (7) Defecation or action of large intestine. Brief statement of the character of each. 134. Organs concerned in the execution of this function as exhibited in different classes of animals. (1) Animals without any special digestive apparatus, and either absorbing food which is already sufficiently comminuted, or else having their whole tegumentary surface capable of secreting a digestive juice ; as the Sponge tribe. (2) Animals without any permanent stomach, which when feed- ing bend themselves around their food, and make an extempora- neous stomach of their skin : as the Amoeba, a naked Rhizopod. (3) The entire animal a mere self-moving stomach with a single orifice surrounded by prehensile tentacula, as the Hydra. (4) Similar to the last, except that the stomach is suspended in a peritoneal cavity. Actiniform Polypi. (5) Stomach with radiating tubes for diffusing the digested mat- ters, and thus increasing the extent of absorbing surface. The tubes are either coecal, admitting only chylific matter, the excre- mentitious portion of the food being retained in the central cavity to be ultimately ejected either at the mouth (star-fish,) or by a separate anus at the opposite end of the body, (some annelidans), or some of the radiating tubes themselves terminate in anal open- ings (Pulmograde Acalephans.) (6) Alimentary canal of some length, commencing by a mouth at one end, and terminating by a single anus at the other. The tube may be bent upon itself so as to bring the anus near the mouth, as in Molluscans; mouth sometimes organized for suction, but most frequently adapted for cutting, filing, or trituration by means of horny Mandibles and jaws, or by means of a special dental apparatus found in a few invertebrates, and in all verte- brates, except Birds and Chelonian Reptiles: anus guarded generally by a sphincter muscle; intervening tract generally divided into gullet, stomach, small and large intestine. Glandular appendages, as SYLLABUS, ETC. 71 salivary, gastric, biliary and pancreatic glands secreting fluids that are subservient to digestion. Follicles of Lieberkuhn secreting a pro- tective mucus, andPeyer's glands, organs of depuratory excretioD. 135. Changes of the food effected in the Mouth. Mastication, its mechanism and its uses; difference in function between the separate classes of teeth. Indications furnished by the character of the teeth i in man of his adaptation for an omnivorous diet. In salivation ;—-4^ sensible and chemical characters of saliva ; rate of secretion. Its ■ manifold uses in digestion, and especially its influence in trans- forming starch into dextrine and grape sugar. 136. Passage of food into the stomach. Three stages of deglu- tition ; mode of protecting the Larynx and the posterior nares during the passage of food through the fauces in the second stage. 137. Chymification or Digestion in the Stomach. Structure of the stomach in man, and especially the minute structure of its mucous membrane and of the gastric glands; sensible and chemical char- --f-j acters of the gastric juice ; circumstances under which it is secre- ted normally; stimuli which increase or diminish the amount; its effects on alimentary substances substantiated by experiments on artificial digestion; nature of the change which albuminous food undergoes; mechanism of the movements of the stomach and their uses. 138. Influence of the nervous system on gastric digestion. This is threefold; (1) in giving rise to the sensations of hunger and thirst which induce to the taking of food; (2) in influencing the secretion of gastric juice as to its amount, and probably also as to its quality, either directly, or indirectly through the sympathies of the stomach with the organ of taste more especially ; (3) in deter- mining the movements of the stomach and the passage of food into or from this organ. 139. Changes of food in the Intestines. Structure and secre- tions of the intestinal tube; Brunner's glands ; follicles of Lie- berkuhn ; Peyer's glands; Pancreas and its secretion; Liver and its secretion ; influence of these several agents in digestion ; two- fold nature of the biliary secretion as a digestive agent and a depuratory excretion ; changes of the food in the large intestine ; movements of the intestinal tube; defecation, &c, &c. Summary recapitulation of the Physiology of Digestion. 140. (1) Digestion of Albuminous or Proteinaceous food, which by the action of the stomach is converted into a low kind of albumen, being at the same time dissolved. Explanation of this act by Muller, who ascribes the solvent property to muriatic acid, the pepsin being held to act as a dynamical stimulus; Liebig's theory, who compares the phenomenon to one of fermentation, the pepsin acting the part of a ferment. Another stage of the diges- tive acts accomplished in the intestines; precipitation of the un- digested particles of food by the influence of bile, some of the 72 SYLLABUS, ETC. constituents of which unite with the precipitated mass to consti- tute the Faeces, the others uniting with dissolved albumen and with fat in emulsion to form chyle. The preliminary processes serve to put the food into more advantageous relation with the gastric juice. (2) Digestion of fatty aliments. Not a chemical but a mechani- cal change; an emulsion formed under the influence of Bile and Pancreatic Juice in the small intestine; in the stomach they are melted, and if taken as adipose tissue the fat cells are ruptured. (3) Digestion of the neutral Hydro-Carbons. Gum, sugar, &c, very soluble, hence their gastric digestion would appear to be a simple solution. After being absorbed by the Portal veins they un- dergo a chemical change in the Hepatic circulation, being con- verted into the fatty elements of Bile, at least in part. Starch, on the contrary, being entirely insoluble undergoes a true di- gestion in the alimentary passages, being converted under the in- fluence of the saliva swallowed with it, into dextrine and sugar. Final causes of Digestion. A. Special and immediate ; (1) to dis- solve solid aliments ; (2) to convert certain organic compounds into others of similar chemical composition ; (3) to separate the insoluble ingredients by precipitation. B. More remote final causes of digestion, or sources of demand for food; (1) to build up the fabric from the condition of infancy to that of maturity ; (2) to supply the constant waste connected with ordinary nutrition ; (3) to supply the more rapid waste connected with the action of the muscular and nervous apparatus; (4) to furnish fuel for respira- tory combustion; (5) to supply extraordinary expenditures such as occur in pregnancy, lactation, haemorrhages, profuse suppura- tion, &c, &c. For one of these purposes, that namely of main- taining the animal temperature, the nonazotized aliments, whether fats or neutral Hydro-carbons will suffice. For all the other uses we require plastic albuminous compounds. DIFFERENT DIETETIC QUALITIES OF FOOD. 141. (1) Digestibility or facility of undergoing digestion, measu- red by the mean time of digestion in a given amount of gastric juice. But of two substances, one which is less digestible intrinsically may yet be soonest digested in the living stomach, because it may by its sapidity or stimulating character provoke a more abundant supply of gastric juice. Intrinsic digestibility dependent chiefly on the physical properties of the food ; actual digestibility largely dependent on the physiological relations of the food with the living system.. (2) Nutritiousness. Absolute nutritiousness measured bv the percentage of plastic or proteinaceous matter in the "food. But the virtual quality depends on the amount duly digested and assimilated. Hence that which is absolutely richest in nutri- ment may be the least nutritious in point of fact because the least SYLLABUS, ETC. 73 digestible. Hence too the actual nutritiousness of the same ele- ments varies according to the state of the digestive organs. (3) Calorifacient property. The absolute capacity measured by the percentage of alimentary fuel, that is of free carbon and hydrogen, which food contains. But some hydro-carbonaceous compounds being less easily digested than others, may be virtually less calorifacient though absolutely richer in combustible elements, since these must be digested before they can be burnt off. (4) Sapidity. Different kinds and degrees of this property; highly important with reference to the actual digestibility of food, by reason of the sympathy between the organ of taste and the stomach. Hence the value of indirect condiments. Direct condi- ments ; danger of using them too freely. (5) Irritating property. That which causes the morbid con- dition termed Irritation; for example the gastralgia or enteralgia caused by green acid fruit, cabbage, kc. Some articles of diet as mucilage, fyc, are entirely devoid of this quality and are even positively soothing. (6) Stimulating property. Or the power of stimulating the system irrespective of the excitement that may be due to defective digestion, or to excess of nutrition or to local irritation. Pheno- mena remotely analogous to the effects of alcoholic drinks. Lobster, Crabs, &c, sometimes stimulate in this way. ALIMENTARY PRINCIPLES. I. Class—Aliments which are calorifacient but aplastic. 142. (1) Gum=C H O. (2) Sugars; cane sugar=C H 0 12 n n 12 n n sugar of milk =C H 0 and grape sugar =C H 0. (3) Starch n 12 12 12 M 14 = C H 0. (4) Lignine or woody fibre=G HO. (5) Pectine 12 10 10 12 8 8 and Pectic acid= C H 0. (6) Vegetable acids, as acetic, citric, 12 8 10 tartaric, malic and oxalic acids. (7) Oily or fatty matters, as oleine, margarine, stearine, &c. (8) Alcoholic principle=C H 0. II. Class—Plastic or nutritive alimentary principles. 143. (1) Proteinaceous principles. Three varieties all of which are found in both the animal and vegetable kingdoms. Proteine, artificially prepared=C H N 0 . Fibrine=10 Pr. + P-f S. 40 31 5 12 Albumen=10 Pr. + P + S . Caseine=10 Pr. + S. 2 (2) Gelatinous principles. Two varieties, Collin or Gelatine 74 SYLLABUS, ETC. proper, and Chondrin. Sensible and chemical characters; doubt- ful dietetic qualities. (3) Alimentary principles contained in the juice of muscular flesh. AsKreatine; Kreatinine; Inosinic acid; Lactic acid, &c, which are probably both condiments and elements of nutrition. III. Class—Inorganic alimentary principles. 144. (1) Water. (2). Saline alimentary principles. Chlorides of sodium and potassium, alkaline phosphates, sulphates, lactates and carbonates, all of which are soluble, and phosphates of lime and magnesia which are insoluble. Inasmuch as iron is a necessary ingredient of the blood, some of its salts must be contained in our food; otherwise disease ensues, which can only be relieved by the administration of ferruginous tonics. 145. Changes of food produced by the different culinary pro- cess. (1) Boiling ; difference of effect according as the meat is plunged into water already boiling, or into cold water which is gradually raised to the boiling temperature. (2) Roasting. (3) Broiling. (4) Baking: (5) Stewing. (6) Frying. COMPOUND ALIMENTS. I. Animal Food. 146. (1) Mammalia furnish a number of solid tissues for the food of man, while the milk of a few species, especially the cow, is also employed. The most important is muscular flesh streaked with fat, containing fibrine, albumen, gelatine, and the sapid juice. Bones, fibrous tissue, cartilage, brain, liver, kidneys, pancreas, thymus gland, stomach of ruminants, (tripe) and skin are likewise used. Notice of the principal kinds of meat, beef, veal, mutton, lamb, pork fresh and cured, &c. &c. Composition and dietetic qualities of cow's milk; composition and dietetic qualities of cheese. (2) Birds.—Muscular flesh, viscera and eggs; dietetic qualities varying with the species. (3) Reptiles.—Eggs and flesh of several species of the Chelonia highly esteemed, but they are rich, stimulating and often irritating. (4) Fishes.—Smaller species eaten whole ; of the larger, all the viscera except the ovaria (roe), are rejected; dietetic qualities varying with the species; very irritating, or even poisonous when not fresh. (5) Crustaceans.—Lobster, crab, shrimp, prawn, &c, have a white firm flesh difficult of digestion; apt to irritate, highly stimulating. (6) Molluscans.—Oysters, clams, snails, &c, &c, nutritive and stimulating, but often difficult of digestion, j SYLLABUS, ETC. 75 II. Vegetable Food. 147. (1) Farinaceous or amylaceous vegetables.—Two varieties ; (a) the cereal grains, as wheat, rye, barley, &c.; composition of wheat flour. Unfermented bread. Fermented bread; mode of preparation; liability to turn sour, &c. Why stale fermented bread is more Avholesome than hot or fresh bread, (b) The legu- minous seeds, as peas, beans, &c, containing besides starch, a large amount of legumin (vegetable caseine), but deficient in some of the important saline principles, (c) Under the head of farinaceous aliments ought to be included some tubers, such as the Irish potato, because of the large amount of starch which they contain. 2) Oily seeds. Almonds, hazelnuts, filberts, walnuts, &c, &c. 3) Fleshy fruits. Apples, peaches, plums, pears, apricots, cherries, &c, &c, &c. (4) Vegetable roots and tubers. Turnips, parsnips, carrots, beets, &c, &c. (5) Buds and young shoots. Onions, shallots, asparagus, &c, &c. (6) Leaves and leaf stalks. Cabbage, cauliflower, broccoli, lettuce, &c, &c. (7) Fungi or mushrooms. Most species poisonous, even the edible species are difficult of digestion and when digested are very stimulating. III. Liquid compound aliments. 148. (1) Mucilaginous drinks, or solutions of many of the varieties of Gum; demulcent and calorifacient; but may turn sour, espe- cially when flavored with sugar. Gum Arabic; slippery elm; flaxseed ; barley water ; Mexican seed; toast water; varieties of gruel. (2) Aromatic or astringent drinks.—Tea; its composition and physiological effects. Coffee ; chocolate ; cocoa; broma. (3) Acidulous drinks.—Lemonade; tamarind water; straw- berry acid, &c, &c. (4) Animal teas, containing only the juices of meat separated from the flesh previously finely divided, by long simmering in water kept a little below the boiling point, in order to avoid a solution of the gelatine; as beef tea, chicken water, &c.; sapid, easily absorbed and probably nutritious. (5) Soups have dissolved gela'tine for their basis, and there- fore the flesh must be boiled. Portable soup or stock; dietetic qualities of soups. SYMPATHIES OF THE DIGESTIVE ORGANS. 149. State of the system coincident with the feeling of natural 76 SYLLABUS, ETC. hunger and thirst. Debility and diminished action of all the organs except those concerned in absorption, which process being physical and dependent on the state of the blood-vessels as to fulness, is more actively performed. Hence danger of exposure to malaria on an empty stomach. Diminution of bodily tempera- ture ; diminution of secretions ; but the gastric and salivary glands are in a condition to respond actively on the first application of a normal stimulus. 150. Phenomena of prolonged fasting and starvation. May be conveniently divided into three stages or degrees. (1) Intense feeling of hunger; sense of great debility, which is, however, mainly sympathetic. (2) Dragging pain at epigastrium ; dryness of throat and fauces ; acidity of saliva; urine scanty and acrid ; redness of the eyes, &c, &c. (3) Phenomena which precede death, varying according as the demand is most urgent for plastic or calori- facient food. In the former case furious delirium succeeds the phenomena above mentioned. In the latter the proximate cause of death is depression of the animal temperature, and is attended by a passive quietness and torpor in striking contrast with the fierce excitement characteristic of the death from want of plastic nutriment. 151. Physiological effects of healthy digestion.—Feeling of sat- isfaction and increased strength; glow at the epigastrium radia- ting over the system ; slight increase in the heart's action and the energy of respiration; organ of taste loses some of the keenness of its susceptibility; deglutition becomes more difficult; limit to the quantity of saliva and gastric juice. 152. Physiological effects resulting from the habitual use of aliments defective in quantity or quality. See Carpenter's Elements, § 416 to § 421. 153. Physiological effects of overloading the stomach. Sensation of painful distension ; nausea; torpor; chilliness, or perhaps fever ; liability to irritation, which is soonest relieved by an emetic of warm water, if the offending substance had not passed the stomach, or by an active purgative if it had. 154. Physiological effects resulting from the frequent or habitual digestion of more food than is needed for the wants of the system. —These vary according as the excess consists, (1) of albuminous or plastic food. (2) Of fat, or substances convertible into fat. See Carpenter, loc. cit., § 421—§ 426. VARIETIES OF DIET AS SUITED TO DIFFERENT CLASSES OF INVALIDS. 155. (1) Cooling and abstemious regimen. Often required in cases of fever, &c. ; acidulous drinks; but their irritating qualities must be guarded against wherever there is liability to gastric or intestinal irritation. SYLLABUS, ETC. 77 (2) Soothing or demulcent diet ; required when the alimentary, urinary or respiratory passages are irritated or inflamed; such as the different mucilaginous drinks. See § 148. (3) Light plastic diet, which shall tax the digestive powers but little, and yet subserve nutrition. Animal teas ; water crackers ; stale bread ; boiled milk, &c. (4) Ordinary diet. (5) Generous or rich diet.—Boiled eggs ; tender and juicy meat broiled or roasted ; oysters, especially if roasted ; porter or ale ; for persons reduced by profuse suppuration, loss of blood, lactation, &c, who yet have good powers of digestion. (For a full exposition of the proper dietetical rules as to the most suitable times of eating, the quantity to be taken at a meal, the character of the different meals, the condition to be observed before and after eating, and the due regulation of the bowels, the students are referred to the admirable treatise of Andrew Combe on "Digestion and Dietetics") FUNCTION OF CHYLOSIS AND LYMPHOSIS. 156. Definition and enumeration of organs concerned.—(1) In- testinal villi, containing each a loop of lacteal vessels and a group of absorbent cytoblasts, which during absorption become developed into cells. (2) Lacteal and other lymphatic vessels with their appended glandulee especially the mesenteric. See Carpenter's Elements, § 489 to § 505. 157. Explanation of the Function___The term chylosis ex- pressive of a double act; (1) the passage of soluble matters from intestinal canal into the lacteal vessels. (2) The transformation of the digested but yet unvitalized matters into living chyle. So also for lymphosis. Notice of the phenomena exhibited during the execution of the function by different vessels, as (1) by the lacteals. (2) By other lymphatic vessels. (3) Properties of chyle and lymph. (4) Office of the lacteal and lymphatic vessels and glands. (5) Absorption by the veins. See Kirkes ' PHYSIOLOGY OF THE SENSORY GANGLIA. 208. Comparative anatomy of the Encephalon.—(1) Fishes. Four ganglionic masses, namely, from before backwards, olfactory ganglia, cerebral ganglia, optic ganglia and cerebellum. The cerebrum of most fishes probably homologous with the corpora striata of man, and not with the true cerebral hemispheres. (2) Reptiles.—Cerebrum larger than any of the other ganglia, and consists of true cerebral hemispheres developed over the corpora striata with lateral ventricles between them. Cerebellum of variable dimensions. (3) Birds.—Cerebrum very much larger than the other masses covers in the olfactory and in part the optic ganglia also. Ceie bellum large and striated. (4) Mammals.—Cerebrum still larger, covering entirely the optic as well as the olfactory ganglia, and in part also the cere- bellum, which in man alone is completely covered by the cerebrum. In all but the Implacentalia the two cerebral hemispheres are con- nected by the great transverse commissure called the corpus callosum. 209—Enumeration of the sensory ganglia.—(1) Olfactory—(2) optic, (Tubercula Quadrigemina). (3) Auditory, (a mass of vesi- cular matter at the roots of the auditory nerve on the floor of the Uh ventricle. (4) Gustative, a small mass of cineritious substance at the root of the glossopharyngeal nerve into which a part of the sensory root of the 5th pair may also be traced.) (5) Ganglion of common or tactile sensibility. The optic thalami, receiving the greater part if not the whole of the sensory tract coming up from the medulla oblongata, probably stand in the same physiological relation within the nerves of common sensibility which obtains between the other sensory ganglia and the nerves of the special senses. # Carpenter associates the Corpora striata with the optic thalami;^ but it is more probable that they are independent centres of motorial power, having a connection with all the sensory ganglia through which they are commonly excited. The muscular actions of man being chiefly guided by tactile sensations, especially those seated in the muscles themselves, the corpora striata have a closer SYLLABUS, ETC. qo connection with the optic thalami than with the ganglia of snecial sensation. F 210. Functions of the sensory ganglia.—(1) Centres of Sensa- tion, but not of Perception, the former being wholly a subjective process, while by the latter the mind takes cognizance of objective realities. (2) But the sensory ganglia, (or rather, perhaps, the corpora striata connected with them) are also centres of motor in- fluence which is reflected involuntarily in respondence to sensorial impressions (consensual or sensori-reflex acts). 3. And further the sensory ganglia exercise a sort of control over even the vol- untary movements in so far as sensations are necessary to guide the will as to the extent and direction of its action. Examples stated and explained. Such operations are wholly different from the simple sensori-reflex phenomena and ought not to be confounded with them under the common term "consensual," as Carpenter seems to have done. 211. Proof of the assigned functions.—(1) Effects of removing the cerebral hemispheres, so as to show that the power of sensation may be retained. (2) Effects of removing any one of the sensory ganglia in permanently destroying the sensibility peculiar to its action and temporarily impairing the motorial powers. The im- pairment consists not in the loss of the control of the will over any muscle, but in an inability on the part of the animal to regulate its actions so as to maintain steadiness of gait. Examples cited and explained. 212. The animal Instincts are assigned by Carpenter to the sensory ganglia on the following grounds. (1) The instinctive acts are involuntary, and are performed in immediate respondence to sensations, that is, they are consensual. (2) The animals most remarkable for the variety and scope of their instincts, namely, the class of insects, have no cerebral hemispheres, their supra- cesophageal ganglia corresponding to the sensory ganglia of ver- tebrates. But the definition of Instinct implied in the first of these statements leaves out of view that which is in fact its very essence, namely the peculiar mental impulse that prompts animals to perform acts (often involving a complicated series of voluntary as well as of involuntary movements) subservient to their own well- being or that of their unborn progeny, but exhibited under such circumstances as to preclude the idea that they could possibly for- see such result. There is an admirable adaptation of means to secure useful ends, but the adaptation is contrived not so much by the animals as for them. And yet, though the instinctive propensity be thus implanted, the acts whereby the propensity is gratified may be and often are strictly voluntary in the physiological sense of the term. The peculiar instincts of animals are, therefore, to be con- trasted, not with the volitional power, but with the reasoning facul- ties, by which man compares, judges, discriminates and adapts means to secure a forseen end. Tests of instinct as contradis- tinguished from reason. (1) The uniformity of the means by 94 SYLLABUS, ETC. which animals of the same species accomplish the same ends, even where they have been secluded from the moment of their birth from all intercourse with their fellows, and often too when a change of circumstances has rendered such means nugatory. (2) The per- fection of the adaptation which often defies all attempts at successful rivalry on the part of reasoning man, this perfection being attained without previous training. Thus the instincts of animals have more points of analogy with the intellectual and moral faculties than with the animal faculty of sensation, and hence it is presumable that they are located in the cerebral hemispheres rather than in the sensory ganglia. Nor is this conclusion invalidated by Carpenter's second proposition, for if it be shown that certain insects manifest some degree of intelligence, his anatomical doctrine of the non-existence of cerebral hemis- pheres in this class of animals falls to the ground. Examples cited from Alison (Cyclopedia of anatomy and physiology) Kirby and Spence, Huber and others, of acts executed by bees, ants, &c, which have all the distinctive characteristics of reason. FUNCTIONS OF THE CEREBELLUM. 213. (1) Comparative development of the organ in the different vertebrate classes. (2) Effects resulting from the removal of one or both lobes of the organ. (3) Effects of disease. Acute disease generally attended with symptoms of apoplexy, and reveals nothing as to the characters of the special functions of the cerebellum. Chronic disease of the cerebellum rare. Yet the few cases re- corded confirm the conclusion derived from comparative anatomy and experiments, that the cerebellum has for its office to coordinate the combined muscular actions necessary for executing locomo- tion, Sfc. 214. Phrenological doctrine as to the office of the cerebellum, that it is the seat of the sexual instinct, refuted by the foregoing considerations. And besides, the alleged facts on which the doctrine is supported are disproved by later and more accurate observers. Thus it is not true that the castration of young males is followed by atrophy or arrest of development of the cerebellum, but the contrary effect is sometimes produced, as shown by Leueet and Lassaigne, who found that the average weight of the cerebel- lum in 21 geldings was 70, that of the same organ in 10 stallions being 61; the superiority of the former being probably due to their employment for draught and to the consequent habitual exercise of the organ in connection with that of the motorial powers. Nor is it true that there is such a frequent coincidence between diseased states of the cerebellum and functional disorders of the genital organs as to favour the phrenological doctrine, for out of 178 cases collected by Burdach, only ten, or but little more than one in 18, presented such coincidence. Probable explanation of the coinci- SYLLABUS, ETC. 95 dence when it exists. Finally there is one case on record in which the sexual propensity was strongly manifested, and yet the cerebellum was entirely wanting. (Cruveilhier's Pathological Anatomy, 15th livraison.) FUNCTIONS OF THE CEREBRAL HEMISPHERES. 215. Structure of the cerebral hemispheres in man. A stratum of cineritious matter 3-16th of an inch thick, forming the super- ficies of the brain, and overlying a contained mass of white matter, which consists (1) of diverging fibres radiating from below upwards through the corpora striata and optic thalami towards the surface; and (2) of converging fibres returning as it were from every part of the surface and crossing the middle line to connect correspondent points of the two hemispheres. These last are called commissures. The former may be commissures between the corpora striata and optic thalami on one hand, and the cerebral hemispheres on the other. 216. Functions of the hemispheres ascertained (1) by the me- thod of exclusion—(2) by evidence derived from comparative anatomy. Pretty regular gradation of development from class to class among all the vertebrata, and from the lower to the higher orders of the mammalian class. There is no such gradation as to the powers of sensation and motion, but there is a correspondent- ly progressive development of intellectual and moral powers. Thus fishes have corpora striata and rarely a perceptible trace of cerebral hemispheres, and are almost or wholly destitute of intellec- tual faculties. A few families (as the squalidse for example,) rise above the piscine standard of psychical endowment, and these are remarkable for a greater development of the hemispheres. Exam- ples cited from the other vertebrate classes. The average weight of the human encephalon in proportion to that of the body is about as 1 to 40. The average of a large number of mammalian orders, is 1 to 186; of birds, 1 to 212; of reptiles, 1 to 1321, and of fishes, 1 to 5668. Apparent exceptions : in the goldfinch the proportional weight of the encephalon compared wTith that of the body is as 1 to 24, and the field-mouse as 1 to 31; but the great relative weight of the encephalon in these and some similar cases is not due to superior development of the cerebral hemispheres, but only to that of the sensory ganglia. The true cerebral hemis- pheres are larger in man in proportion to the whole encephalon, to the whole of the nervous system, and to the whole body, than in any other animal. (3.) By evidence derived from experiments— effects resulting from the removal of the hemispheres—effects pro- duced by removing the cerebellum and sensory ganglia, the cere- bral hemispheres being left entire. (4.) Evidence derived from pathological observations on man. Extensive lesion of the surface of both hemispheres always attended with mental aberration, d6 SYLLABUS, ETC whereas extensive disease of other parts of the encephalon may exist without any impairment of intellect. 217- Conditions of the action of the cerebral hemispheres— encephalon receives nearly or about one-fifth of all the blood in the system—arrangement of the arteries at the base of the brain for insuring an active arterial circulation through the organ and at the same time preventing any sudden and violent impulse of the blood upon the cerebral substance when the heart's action is sud- denly increased. A certain amount of pressure also necessary, which is equalized by means of the easy displacement of the cere- brospinal sub-arachnoid liquid. 218. Connection between the mind and the cerebral or- ganization. Statement of the opposed doctrines of material- ism and spiritualism. Physiology lends no countenance to the former, while the latter seems to be a legitimate induction from the facts of consciousness. It is held by the materialist (1) that inas- much as the mental faculties are developed pari passu with the development of the brain, partake of its disorders and cease to be manifested when it ceases to act, hence mind is nothing but a set of faculties attached to the brain in the same way as contractility is a faculty attached to muscle, or electricity a set of properties attached to sealing wax and other bodies. But all these facts are equally well explained on the hypothesis of a separate mental entity operating through the brain as its instrument. (2.) That there is no evidence of the existence of mind in a state separate from organization; to which it has been well replied, " that the whole universe displays the most striking proofs of the existence and operation of intellect or mind, in a state separate from or- ganization, and under conditions which preclude all reference to or- ganization." (3.) That the weight of proof rests with those who assert the independent existence of a mental entity ; to which it may be replied, that since the belief in mind as separate from mat- ter is one of those "first truths" which constitute the "primary elements of human reason," it devolves upon those who deny the validity of such intuitions to sustain their position, which thus ap- pears to be at variance with the common and instinctive belief of mankind. But further, as regards material phenomena we observe that they have all "a certain relation to each other, so that they may be referred to certain general principles, but no analogy of this kind can be detected with respect to mind" in its connextion with the brain.—The foregoing heads of arguments expanded and illustrated. PHYSIOLOGY OF THE SENSES. 219. Definition of Sensation as that state of consciousness which is excited by the appropriate action of a sensory ganglion, which is usually, but not invariably dependent on a prior impres- sion upon the peripheral expansion of a sensory nerve. Exclu- SYLLABUS, ETC. 07 sively subjective operation of the mind in simple sensation, as PriblJ» m the case of the earlier experiences of infancy 220. Definition of Perception, as the faculty by which the mind refers sensations to an outward cause and forms certain notions with regard to the qualities of the outward agent. Examples. 221. Physiological mechanism of sensation. (1) Impression on the peripheral expansion of a sensory nerve effected in different ways—(2) conducting action of the nerve fibres—(3) action of a sensory ganglion consequent on the reception of the influence thus conducted. Possibility of stimulating the ganglion abnormally so as to supersede the two first processes without altering the char- acter of the resulting sensations, as in dreaming, delirium, con- gestion of the brain, &c. 222. Classification of sensations. I. External sensations, of which there are five kinds, namely, touch, taste, smell, hearing, and sight. II. Internal sensations, resulting from organic changes in the organs independent of direct impressions from without, as flashes of light seen in cases of inflammation of the retina though the eye be excluded from all source of illumination. Hun- ger, thirst, the feeling of lassitude, &c, are instances of in- ternal sensations. All of the internal sensations which are not clearly referrible to one of the special senses are believed to depend on the action of the same nervous apparatus which when impressed by an external agent gives rise to simple tactile sensa- tions, and hence the sense of touch is called the common or gene- ral sense. 223. General physiological laws of perception. I. Every sen- sation of whatever kind immediately attended by certain intuitive general perceptions, as (1) the reference of the sensation to some outward cause, constituting the foundation of our belief in an ex- ternal world, and (2) the location of the impressing agent at the extremity of the sensory nerve, even when in reality the impres- sion has been abnormally applied elsewhere. It follows as a corol- lary from this law that where the elementary fibres of certain sensory nerves (those of touch and sight) may be separately im- pressed the perception of superficial figure will be likewise intui- tive. II. Each special sensation is attended by certain intuitive special perceptions peculiar to its own class. Thus perception of colour is peculiar to the eye. Such perceptions are immediately dependent on the associate sensations, and are independent of the mode in which the nerves are impressed, or of the nature of the impressing agent. Hence the transference of special sensibility from one set of nerves to another is impossible. Electricity ex- cites the action of all sensory nerves, but the resulting sensations are very different in the different cases, in each case being the sensations peculiar to the nerve impressed. III. Therefore the immediate object of perception is not the impressing agent but the change produced by it in the organs of sense, but inasmuch as the organs of sense participate in the properties of matter, having 7 98 SYLLABUS, ETC extension, being susceptible of pressure, motion, alteration of tem- perature, &c, we reason from these changes to the qualities of the agents which produce them and thus have certain acquired percep- tions. IV. While the passive susceptibility of sensation is blunted by habit, the active power of discrimination, or the delicacy of the perceptive faculty is increased by frequent exercise. V. The intensity of the sensation and consequently the distinctness of the perception depends more on the relative than on the absolute change in the sensorium—illustrations : SENSE OF TOUCH. 224. Class of nerves concerned. Proof that tactile sensibility is merely one mode of general or common sensibility. Structure of the skin as an instrument of touch. 225. Varieties of common sensation, external and internal; as tact or pricking, pressure, temperature, itching, hunger, thirst, venereal feeling, coenaesthesis, muscular sense, &c, &c. Special intuitive perceptions connected with such sensations, as the idea of resistance, weight, temperature, as a quality of ex- ternal bodies; dryness or moisture, &c, &c. Tactile perception of superficial figure and dimensions, in what degree intuitive -and to what extent acquired. Assistance derived from the muscular sense in giving greater precision to our intuitive tactile percep- tions. SENSE OF TASTE. 226. Structure of the organ. Physical state of the surface essential to its action. Nerves concerned. The cause of sapidity in bodies only cognizable by its power of impressing the organ of taste. Its varieties as indicated by the terms, sour, sweet, bitter, acrid, &c., &c, as well as the infinite nameless varieties. The perception of the differences between these varieties is intuitive, but the association of each with a certain body or class of bodies is, of course, acquired, and becomes important as a means of distinguishing such bodies. Sympathies of the organ of taste. SENSE OF SMELL. _ 227. Proof of the olfactory sensibility of the first pair of cran- ial nerves. Physical condition of the pituitary membrane es- sential to the exercise of this function. Use of the antrum and other sinuses. Physical cause of odors. Varieties of odors. Intuitive perception of these variations. Acquired perception SYLLABUS, ETC 99 of other qualities of bodies by means of their association with peculiar varieties of odors. Affinity between the sense of taste and smell. SENSE OF HEARING. 228. Anatomy of the apparatus of hearing in different animals. (1) A simple sacculus on the inner walls of which the auditory nerve is distributed, imbedded in the flesh without any fenestral opening into the chamber; as in gasteropods and cephalopods. (2) The same kind of sacculus lodged in a chamber which has a fenestral opening closed with a vibratile membrane; as in the basal segment of the lesser antennae of certain crustaceans. (3) Fishes have, in addition to the sacculus, a vestibule and semi- circular canals of which except in the lowest order, there are always three arranged as in man. The whole apparatus lodged in a depression of the inner surface of the cranium, which communicates with the cranial cavity, except in the higher cartilaginous fishes. (4) Reptiles have rudimental cochlea, fenestra ovalis, stapes, and all but the lower amphibians and ophidians have a tympanic cavity. (5) Birds have a more highly developed cochlea divided into two scalse although still straight, fenestra rotunda, tympanum, colu- mella, &c. (6) Mammalia have a spiral cochlea and an external ear or auricle in addition to the parts existing in the lower classes. Proof of the special character of the portio mollis nerve. 229. External cause of sounds. Modes of propagating sonorous vibrations from the sounding body to the ear. (1) Conduction by progressive vibrations excited by the stationary waves in which the sound originates. Loss of energy in the transference of pro- gressive vibrations from one medium to another of different physi- cal nature. (2) Reciprocation, or the excitement of secondary stationary vibrations in certain bodies which are particularly sus- ceptible of such action, particularly organic membranes and strings made elastic by tension, when they are placed near to, but not in contact with sonorous agents with which they can vibrate in unison. Conditions necessary for the production of these secondary re- ciprocating vibrations, which giving an additional impulse to the air, increase the intensity of the sound as produced by the primary sounding body. Water conducts the vibrations thus produced in reciprocating solids, and thus we obtain a means whereby sound may be imparted from air to water. (3) Resonance, consists in increasing the extent of surface of a soniferous medium, similar in kind to the primary sounding body. It is thus, a kind of reciprocation, but differs from the foregoing in this, that the sounding board must be in contact with the sonorous body, and need not have the peculiar susceptibility of organic membranes. Resonance much favoured by the insulation of the resonant medium. 100 SYLLABUS, ffJC. 230. Mechanism of the ear in audition, and uses of the several parts of the complicated apparatus. The essential part of an organ of hearing being a nerve of special endowments, so disposed as to receive sonorous impressions to the greatest advantage, it will be more natural and easy to consider the uses of those parts which exist in all the varieties of such apparatus, and those of the superadded structures in the order in which they successively ap- pear. (1) Uses of the endolymph; probably, to maintain on the surface of the nerve the same physical condition which necessarily exists in its interior parts. (2) The sacculi and the ear dust. " Sonorous vibrations are not only imparted from water to solid bodies bounded by definite surfaces which are in contact with the water, but are also returned with increased intensity by these bodies to the water, so that the sound is heard loudly in the vicinity of those bodies in situations where, if it had its origin in the conduct- ing power of the water alone, it would be faint."—(Muller). Ex- perimental evidence of the effect produced by solid bodies floating in the liquid of a sac whose walls are thrown into vibration. (3) Perilymph and fenestra ovalis with its membrane. The latter a reciprocating medium by means of which vibrations of the air are transferred to water which is the final impressing agent. (4) Semi- circular canals. Conjectural view of their office as connected with the perception of the direction of sounds. (5) Cochlea—supposed to be an arrangement for the advantageous reception of the vibra- tions conducted by the bones of the head. Spiral form, not essential and exists only among mammals, being, as is probable, an arrangement for convenience of package. (6) Fenestra rotunda and its membrane. This membrane and that of the fenestra ovalis being unequally distant from the auditory nerves the phe- nomena of "interference" of the sonorous waves ensue, whereby there is occasionally produced a more intense impression on the nerve. (7) Tympanum, with its ossicles. The vibrations of the air may be communicated to the perilymph by the simple interpo- sition of the membrane of the fenestra touching the water on one side and the air on the other, but in a far more perfect manner, as proved by experiments, by connecting this membrane by means of a rod with a second membrane having air on both sides, par- ticularly if the rod be insulated in a space bounded by definite walls like the tympanum. Explanation and application to the case of the natural tympanum. (8) 3Iechanism and uses of the membrana tympani, as adjusting the ear to sounds of different degrees of in- tensity and pitch. Experimental method of increasing the tension of this membrane, by a voluntary effort and its effect in blunting the sensibility of the ear for all except very acute tones. (9) Eustachian tube serves to carry off secretions, and also to main- tain an equilibrium of pressure on the two sides of the membrana tympani. (10) Mastoid cells are resonant cavities. (11) Auditory canal a resonant medium, both by the air in its cavity and by its walls, which also conduct the vibrations of (12) Auricle, a recipro- SYLLABUS, ETC. ,101 eating instrument with various inflexions of its surface of which the probable use is to receive the progressive undulations at right angles from whatsoever direction they come. The concha with the auditory canal forms a hearing trumpet. 231. Perceptions connected with the exercise of this sense (1) Of the variations of intensity of sound. (2) Of musical pitch, which is dependent on the number of vibrations in a second, or rather on the interval between two successive impulses, as exempli- fied by experiments with the "siren." Physical condition of harmony and melody. The "musical ear" whether dependent on the conformation of the ear or on the organization of the brain. (3) Tone or timbre, varies with the physical nature of the sound- ing body, &c. Physiology of Sight. 232. Possible forms of organs of vision. The sensation and perception of luminousness may exist without any optical appa- ratus, and require only the presence of a nerve with special en- dowments. In general, however, we find associated with such a nerve one of three forms of optical apparatus for supporting the nervous expansion and for concentrating or otherwise modifying the luminous rays. (1) Ocelli or Eye-dots, found in many of the Annelida and in the larva state of many insects, &c. (2) Com- pound eyes of insects and crustaceans, of which there are several varieties. (3) Simple eyes of cephalopod molluscans and all the vertebrate classes. 233. Optical principles involved in the exercise of the eye as an organ of vision. (1) Physical cause of the visibility of bodies. Self-luminous bodies and bodies luminous by reflection. (2) Ra- diation of light in all directions from a luminous centre and its passage in straight lines so long as it is in the same medium. (3) Laws of reflection of light from the surface of bodies—opake and transparent bodies. (4) Laws of refraction. Index of re- fraction or the ratio of the sine of the angle of incidence to that of the angle of refraction constant for all angles, the media being the same. (5) Effect of the convexity of a refracting medium in causing diverging incident rays to converge on passing out. (6) Relation between the distance of a luminous point in front of the lens and focal distance. (7) Aberration of sphericity—how obviated. (8) Aberration of refrangibility or dispersion of colored rays. Achromatism, how obtained. (9) Mechanism of the ca- mera obscura. 234. Mechanism of the human eye. A globular camera ob- scura. Advantage resulting from the globular form. Cornea, aqueous humour, crystalline lens and vitreous humour appear to form an aplanatic and achromatic combination. Fluidity of the aqueous humour necessary for admitting the movements of the 102 SYLLABUS, etc. iris, a diaphragm or stop for cutting of the peripheral rays when the light is too intense, or when looking at very near objects when spherical aberration would be likely to ensue. Muscularity of the the iris and its mechanism. Adjustment of the eye to vision at different distances, probably by the agency of ciliary processes and the ciliary muscle. 235. Explanation of the phenomena of vision. (1) Simple per- ceptions of light dependent on any adequate excitement of the organ of vision though the sensation be entirely internal and be produced in perfect darkness. This is probably the sole function of certain forms of ocelli. (2) Simple perception of colour. Phy- sical explanation of the colour of transparent and opake bodies. Physiological explanation of the perception of colour, according to the undulatory theory. Complementary colours. Colored spectra whether positive or complementary, and their physiological explanation. (3) Perception of the position of a luminous point; size of aliquot portions of the retina possessing the power of in- dependent sensation; law of visible direction. (4) Perception of superficial extension shewn to be a necessary consequence of the fore- going law and therefore intuitive. Error of Locke and other meta- physicians in denying the identity of tactile and visual percep- tions of plane figures, whereas only the sensations and not the con- sequent notions differ. See case of young man restored to sight by an operation for cataract, performed by Dr. Franz and recorded in the London Philosophical Transaction for the year 1841. (5) Per- ception of solidity. With the use of one eye only this perception must be acquired; but with both eyes the notion is intuitive. Mechanism of the stereoscope invented by Wheatstone; physio- logical interpretation. (6) Single vision when both eyes are used. Theory of identical or correspondent points on the two retinae with the assumed physiological explanation. Objections to the theory. (7) Erect vision, the image on the retinae being inverted, does not need explanation, since the images of all surrounding objects that might be used for comparison, are likewise inverted. (8) Esti- mate of the size of visible objects. Actual and ideal size of the field of vision; " visual angle'' or measure of the size of the image on the retina dependent on the size and distance of the visible object. Hence when the latter element is not known we are sub- ject to deception in our estimate of the former. (9) Appreciation of distance determined in part by visual angle when the size of an object is previously known. Angle of convergence of the axis of the two eyes. Interposition of known objects. Variations of the intensity of light and shade. (10) Visual perception of the motion of objects. (11) Duration of visual sensations giving rise to lu- minous spectra. (12) Vanishing of images which fall at the entrance of the optic nerve. (13) A7isual representation of the retina itself by the experiment of Purkinje. SYLLABUS, ETC 103 SPECIAL PHYSIOLOGY OF THE CEREBRO-SPINAL, AND OF THE SYMPATHETIC NERVES. 236. Method of determining the special functions of a nerve. Effects resulting from the experimental irritation of a nerve ac- cording as it may prove to be a nerve of motion, or of sensation, or an afferent nerve belonging to the physico-reflex system. Effects resulting from the section of a nerve belonging to either of these classes. 237. Functions of the spinal nerves at their anterior and pos- terior roots. Subsequent mingling of the fibres in trunks and branches of mixed functions. Formation and function of the phrenic and other spinal nerves. 238. Physiological classification of the cranial nerves. Reference to the text-book for a detailed account of the functions of each. 239. Reference to text-book for account of the actions of the Sympathetic nerve, the office of which is, probably, to establish a harmony of action between the organic operations of distant parts. Sometimes this is accomplished by means of physico-reflex movements, of which the nervous centre is one of the sympathetic ganglia, as seems to be the case with the peristaltic movements of the intestinal canal. But frequently the sympathy is exhibited by an exaggerated, diminished, or perverted secretion, or act of nu- trition, which cannot be explained by supposing that the reflected nervous influence operates on the muscular function of the small arteries. We must, therefore, admit that some efferent nerves convey an influence which operates on the nutritive functions directly. It is true that this influence is not essential to the per- formance of the nutritive acts, as has been erroneously represented by Paget, but it is capable of accelerating, retarding or modifying the character of those acts. Examples cited. 240. Summary recapitulation of the physiology, general and special, of the nervous system.—The final causes of the nervous functions may be summed up as follows:—(1) As subservient to the excitement of those movements of animals which depend upon stimuli not felt but reflected from an impressible surface, through a circle composed of an efferent nerve, a ganglionic centre and an efferent nerve, to distant muscles, (physico-reflex movements.) (2) As subservient to the manifestations of the conscious mmd and to bringing it into relation with the external world, either by receiving sensorial impressions which give rise to certain fundamental ideas of perception or by reacting on matter through the instrumen- tality of the motorial apparatus stimulated by sensations, (sensori- reflex or consensual), emotions (emotional), thoughts (ideo-motor), or the will (volitional movements). (3) To establish a harmony of action between different parts of the system. See above, § 239. 104 SYLLABUS, ETC. PHYSIOLOGY OF THE SENSIBLE MOTIONS OF ANIMALS. 241. Locomotion occasionally though rarely exhibited by vege- table structures, and only strictly peculiar to animals as executed in respondence to stimuli acting through a nervous system. Con- tractile cells of certain vegetable structures—phenomena of ciliary motion (see § 27).—In both these cases the action seems to be inherently rythmical, that is, a single excitement is adequate to give rise to a prolonged series of contractions alternating with re- laxations. 242. General Physiology of muscular action. Statement of the functions—(1.) Sudden and rythmical contractions causing the displacement of moveable parts to which the muscles are at- tached, or the propulsion of matters contained in hollow viscera whose walls are formed by the contractile muscular fibres. (2.) A more slow and permanent contraction which gives tone to the muscle itself and often subserves the office of regulating the calibre of tubes around whose walls the contractile fibres are circularly disposed. Explanation. I. Rythmical contractions excited normally by nervous influence, but may be excited by direct mechanical or chemical stimulation of the fibres themselves. The proximate cause of such contractions is a peculiar inherent vital property which has been called irritability, but is more appropriately termed contractility, and this endowment of the muscular fibre is an " ultimate fact." Proof of this statement. Laws of muscular contractility—(1.) Disintegration of tissue coincident with each contraction.—(2.) Necessity of active arterial circulation—(3.) necessity for intervals of rest after prolonged action—(4.) force of contraction proportional to energy of stimulation—(5.) de- velopment of heat—(6.) production of a peculiar murmur—(7.) velocity of contraction under certain circumstances. II. Tonic contractions either dependent on a distinct vital property, tonicity, or else on the ordinary contractility kept in a state of sustained operation by the influence of a permanent stimulus. Phenomena of cadaveric rigidity. PHYSIOLOGY OF THE VOICE. 243. The human voice consists of the sounds produced by the air m its passage through the larynx with a certain degree of expiratory force, and in a certain position of the inferior laryngeal ligaments. The organs concerned include not only the whole'res- piratory apparatus with that portion of the nervous system which is subservient to the excitement of the respiratory muscles, but certain superadded parts, such as the pharynx, mouth, tongue,' lips and nasal cavities, which modify the laryngeal sounds so as to SYLLABUS, ETC. 105 constitute articulate language. The special organs are the inferior laryngeal ligaments, therefore called vocal cords, which are thrown into vibration by the impulse of the air in expiration, after being first placed in a vocalizing position by the thyro-arytenoid mus- cles. 244. Preliminary notice of some of the phenomena of acous- tics. Physical cause of sounds and the circumstances which de- termine the pitch, the intensity, and the timbre of sounds. 245. Laws of vibrating strings. The fundamental note being that which is due to the vibrations of the string by its entire length, the number of vibrations for shorter lengths is inversely proportional to the length, thus: Fundamental. Third. Fifth. Octave. No. of vibrations, - 1----1----£----4----§----f----is----2 Length of string, - 1----«----f----J-----|----f----1%----1 Names of notes, - C. D. E. F. G. A. B. C1. The length being constant, the number of vibrations is propor- tional to the square root of the tension. 246. Wind instruments. In these the contained air is the seat of sonorous undulations passing backwards and forwards from one end of the column of air to the other, the rapidity depending on the length of the wave or of the space which it traverses. Hence the number of vibrations is inversely proportional to the length of the tubes. A tube open at its extremity yields a fundamental note an octave higher than a closed one, a nodal point being formed in the mid- dle of the column of air. In either kind higher notes are produced by increasing the force of the blast, but the nearest note to the fundamental one is, under such circumstances, its octave. 247. Instruments in which the properties both of solid and of fluid elastic bodies come into play. Reed or tongued instru- ments. Laws of the vibrations of membranous tongues with superadded tubes. The pitch of such a tongue may be raised almost an octave in successive semitones by altering^ the force and manner of the blast. 248. Structure of the larynx. Classification of the laryngeal muscles. (1) MUSCLES WHICH REGULATE THE TENSION OF THE VOCAL CORDS AND THUS GOVERN THE PITCH OF THE NOTES. f Depress the front of the Thyroid cartilage on the cricoid, Crico-Thyroidei J ftnd sire(ch the vocal cords. Thev are assisted bythe Aryte- Stcrno-Thyroidei | noideus Transversus, and the Crico-arytenoidei postici. Thyro-Arytenoidei / Elevate the front of the Thyroid cartilage and draw it Thyro-Eyoidei \ towards the Arytenoid and thus relax the vocal ligaments. 106 SYLLABUS, ETC. (2) MUSCLES WHICH GOVERN THE APERTURE OF THE GLOTTIS. Crico-arytenoideipostici . . . Open the glottis. Crico-arytenoidei laterales f Press together the inner edges of the Arytenoid Arytenoideus transversus \ cartilages and close the glottis. 249. Position of the vocal cords in simple respiration ; vocal- izing position; mean length of the cords of the adult male, 0.728 of inch in repose and 0.912 in greatest tension. Of the adult female 0.498 and 0.617. Shape of the aperture in different positions of the ligaments and of the arytenoid cartilages. 250. Modulation of the voice. Muller's experiments on the artificial production of the voice with the larynx separated from the dead body. Upper ligaments and epiglottis shown to be merely or chiefly reciprocating and resonant media for increasing the loudness of sound, but not for altering their pitch. Pitch of the notes regulated by the length and tension of the vocal cords. Compass about two octaves. Two distinct series of notes, namely, the ordinary and the falsetto register. The highest notes always belong to the falsetto, and the lowest always to the ordinary register, but if a moderate tension of the ligaments be maintained, it depends on the manner of blowing whether the ordinary or falsetto note be produced, (the latter being most easily produced by blowing very gently,) and the two different notes thus produced may be very distant from each other in the musical scale, even as much as an octave. Muller's explanation of the falsetto notes. ^ Mode of successively raising the pitch of the ordinary voice without run- ning into the falsetto register. Influence of narrowing the diameter of the larynx immediately below the vocal cords, which is effected by the action of the Thyro-arytenoid muscles. Other uses of these muscles. Condition of the vocal cords in the production of different notes from the deepest bass to the highest tenor. SYLLABUS, ETC. 107 I u o w 251. Theory of the voice. The human voice held to be a reed instrument with a double-membranous tongue. When simple vibrating strings are very strongly touched deeper notes are produced, whereas the note given out by a moist membranous tongue is raised by a stronger blast the extent of many semitones. 252. Three different kinds of sequence in the notes of the human voice. (1) Monotonous, as in speaking, only occa- sional syllables receiving a slightly higher intonation for the sake of accent. (2) Successive transitions from high to low notes and vice versa, as in the involuntary cries of pain, &c. (3) Musical sequence. Compass of the voice in different individuals. Varieties of male voice, technically called bass, barytone and tenor, and of the female, contralto, mezzo-soprano and soprano. The ordinary compass of each may be seen on the scale placed in the margin. These different kinds of voice differ also in timbre so as to be distinguished when sound- ing the same note. Difficulty in hitting upon the right note when passing suddenly in singing from the natural to the falsetto register, or from a low to a loud tone. 253. Differences of the voice as to timbre, dependent on the form of the air-passages and on their resonance. A nasal tone may be given in two ways. (1) When the external openings to the nares are closed, the voice may become nasal by the approxi- mation of the arches of the fauces, and by the larynx ascending higher than when the voice has its natural character. ^ Obstruction of the nostrils by mucus has the same effect as closing the ante- rior nares, but neither the one nor the other can alone give the nasal tone to the voice. (2) The nasal twang may also be given when the nostrils are open, the mouth being either open or closed. In this case likewise the larynx ascends considerably ; the arches of the fau- ces contract; and the dorsum of the tongue is approximated to the palate or brought into contact with it; and the air merely passes be- tween the narrowed arches of the fauces and receives the resonance 108 SYLLABUS, -ETC. of the nasal cavities without that of the cavity of the mouth.— (Muller.) Character of the voice at different epochs of life. 254. Strength of the voice as dependent partly on the capability of vibration of the vocal chords and partly on the fitness of the membranes and cartilages of the larynx and of the adjacent organs for resonance. Increased intensity of vocal sounds produced by an increase in the force of the blast; but as this same change alters the pitch of the notes, there must be some means of compensating this tendency to emit a higher note, which probably consists in re- laxing the vocal chords in a suitable proportion. 255. Perfectness of notes. Cause of dissonance after long singing; cause of habitual dissonance. Explanation of the power to reproduce given notes in singing by ear or by note. Musical sounds formed in the mouth as in whistling where the air is the source of the sounds, by friction against the borders of the opening. 256. Articulate sounds or speech. Division of articulate sounds into vowels and consonants and mode of producing each. Mute vowel and consonant sounds. Explosive and continuous sounds. Ventriloquism. SYLLABUS, etc 109 GENERAL CONSIDERATIONS HAVING REFERENCE TO THE CONDITIONS OF VITAL ACTIONS. I.—On the connection between Life and Organization or nature of the Vital Principle. 257. Some of the actions of man the result of mechanical ar- rangements^ of parts endowed with purely physical properties. Examples cited and explained. So also other actions result from the operation of purely chemical forces. But a large number of the actions of the human organs cannot be referred to either of these classes, and are found to indicate the existence of properties or forces peculiar to living organized structures, and accordingly these forces are denominated vital. The investigation of the laws of these forces must be. pursued by the same inductive process which is employed in other departments of positive science. 258. Is there an essential distinction between vital and physical forces ? Two opposing views in regard to this question which is rather speculative than practical. (1) Doctrine of the vitalists who hold that the proximate cause of all the truly vital acts is a special entity which they denominate the vital principle and which they consider to be as independent in its essence of the tis- sues which it animates as the soul is of the brain through which it acts. According to this view a tissue, an organ, or the whole body may die, by reason of the vital principle deserting its ma- terial tenement, though the latter may be uninjured. (2) The advocates of the opposing doctrine hold that the vital properties depend on the structure of organized tissues, just as physical properties depend on the special forms of matter by which they are manifested, the main difference being that the structure of organi- zed tissues is in many of its features so refined and delicate that it can never be successfully imitated and therefore no vital act, not even the simplest, can ever be artificially exhibited. This would seem to be the most philosophical view of the subject, on the simple ground of the entire absence of any satisfactory founda- tion for the opposing doctrine, which also seems to be disproved by the fact that each tissue and even minute fragments of tissue possess independent vitality, which would require us in adopting such a doctrine to admit the existence of several hundred vital principles. Thus Brown—Sequard has shewn that entirely dead muscles of one animal may have their power of vital contractility restored to them by connecting their blood-vessels with those of a living animal of the same species, in such a manner as to cause the circulation of living blood through the previously dead muscle. 259. Examination of the arguments adduced by the vitalists. (1) Unity of the vital acts all of which point to a common pur- pose. But this only indicates the final cause and not the instru- HO syllabus, etc mental method; and the same argument might be used with reference to the operations of any machine exhibiting design, and the skilful adaptation of means to a specific end. It is clear in all such cases that the cause of the unity, lies in the designing mind of the con- triver and architect, who arranges a mechanism with reference to the production of such an effect; and in the case of living machines, it would be not less derogatory to the Great Author of Nature, to ascribe the wonderful unity of plan and purpose to an imaginary vital principle, than to refer it to a property of brute matter. It is just as easy to suppose, that the Almighty uses brute matter as his immediate instrument in the production of vital acts, as that certain intermediate agencies or vital entities are indispensable. Indeed, the latter hypothesis is much the grosser of the two, and seems to have its origin in an unconscious ascription to the Almighty of some of the imperfections which belong to man, namely, the impossibility of acting upon matter except through secondary instrumentalities. Again, if this argument of the vi- talists were valid, then by a parity of reasoning the universe should have its vital principle, since it may be said to be organized in the sense of being composed of diverse but mutually adapted parts, the operations of each of which tend to the stability of the whole, as abundantly shown by writers on natural theology. Accordingly those vitalists who have logically followed out their principles have naturally ended in Pantheism. 260. (2) The limited duration of organized structures, each species of plants and animals having an appointed term of life, is adduced as an argument in favor of vitalism. But it is as easy to believe that the structure of a living body is such as to wear out after a certain amount of use, as that an immaterial principle enters the germ at conception, remains in connection with the growing plant or animal and after a certain time leaves it. 261. (3) The bodies of living animals resist (the vitalists assert) the operation of the ordinary forces of matter, as for example, the tendency to putrefaction, which is restrained by the controlling in- fluence of life, and which ensues immediately after the withdrawal of life. But it may be shown that the ordinary forces of matter are not resisted however their effects may be counteracted by the vital acts. For example a decay analogous to putrefaction is con- stantly going on, but the products are separated from the blood by the depuratory glands, and finally discharged from the body in the form of the different excretions. 262. (4) It is alleged that sometimes life is destroyed without in- jury of the material fabric, as when death suddenly ensues from men- tal emotion, from a stroke of lightning, &c. But this is an unproved and highly improbable assumption. In very many such cases adequate lesions are found in the heart and brain, and when we reflect upon the complicated composition of the blood and of the semi-solid substance of the nervous system, we can readily conceive SYLLABUS, ETC -,..., that there may be many kinds of disturbance incompatible with health, and even with life, and yet not appreciable to the eye 263. ■ (5) Impossibility of artificially exhibiting vital phenomena This is, admitted, for we cannot artificially construct the material frame. The simplest and at the same time the most essential structural element of organization is the primordial cyto-blast or cell germ of so refined a structure and composition as to be inca- pable of exact appreciation. Of course this microscopic body cannot be imitated. The argument can have no value until a per- fect organism has been constructed and then be found to need the Promethean heat of a vital principle. 264. The charge of materialism cannot be fairly brought against the doctrine here contended for, since in rejecting the hypothesis of an independent vital principle reference is had to those vital pheno- mena which man possesses in common with the lower animals, and which are irrespective of the sentient and conscious mind. Where- ever sensation or any other mental act is concerned, it is admitted that an immaterial and independent agent is operating through a material organ. The question here considered is whether the or- ganic acts depend on a similar entity to be called the Vital Princi- ple. The arguments in favor of the immateriality of the sentient and thinking principle do not in the least degree apply to the case in question, but on the contrary the materiality of the phenomena of organic life may be legitimately inferred from their very con- trast with the phenomena of mind. 565. Notice of a metaphysical sense in which vital forces, as mere objects of cognition, may be regarded as distinct from the organized tissues by which they are exhibited. But this is equally true of all forces, physical as well as vital, and cannot give any countenance to the doctrine of vitalism, which affirms the exist- ence of an independent vital entity, but denies the existence of any correspondent inanimate material principle, on the ground of an essential difference between the two classes of acts. 266. In the absence, then, of any proof to the contrary, we conclude that the vital phenomena are the results of vital forces operating through organized matter, precisely as other natural phenomena are the results of physical forces acting through inani- mate matter, and that we have no better reason to ascribe an in- dependent existence to the former than to the latter, but that on the contrary, the remarkable correlation between these two classes of forces constrains us to admit their essential similarity. (See Carpenter's Elements of Physiology, § 52 to § 73.) II.—ON THE EXTERNAL CONDITIONS OP VITAL ACTIVITY. 267. Threefold condition of vital actions—(1) an organism— (2) alimentary materials requisite for the construction and mainte- nance of the organism, and (3) the dynamical conditions, or the 112 SYLLABUS, ETC. forces or powers on which its operations are dependent. Now the vital forces seem themselves to result from the operations of certain phy- sical forces, especially light and heat, on duly organized structures. The higher the organization the greater the dependence on these forces. Their influence rather relative than absolute. Apparent distinction between living bodies and inanimate masses of matters in this respect. The proper interpretation of this fact, as con- nected with the change which the organism itself undergoes by any considerable alteration of the doses of stimuli to which it may be exposed. (a) OF LIGHT AS A CONDITION OF VITAL ACTIVITY. 268. Notice firstly the influence of light as a condition of chem- ical action, sometimes determining the union of bodies, as of hy- drogen and chlorine, and sometimes effecting chemical decomposi- tion. Secondly, its influence on the functional activity of plants, as (1) on the development of the vegetable structures, acting in two ways, namely, by directly exciting the chemical acts concerned in the fixation of carbon and by regulating the action of the sto- mata, so as indirectly to regulate the absorption of fresh material. Hence exclusion of light arresting these processes, causes plants to become pale, succulent and dropsical; a condition which often increases their value as aliments but renders them unhealthy as natural beings. Germination retarded by light, a plant during germination resembling an animal in its relation to heat and con- sequently to carbon, which it then consumes. (2.) Influence of light on the motion of plants, as the direction of the growing stem, the expanding of flowers and their turning towards the source of light. 269. Influence of light on the functions of animals—(1) on the development of the body; Humboldt's testimony with regard to the perfect development of the bodies of savages who go habitually uncovered. Deprivation of this influence seems to be one of the causes of scrofula, rickets and other diseases leading to bodily deformity. Tadpoles prevented from undergoing metamorphosis by confinement in the dark. (2) On the functions of the skin. Ruddy complexion of health belonging to persons living in the country contrasted with the etiolation of inhabitants of the city. An excess of the stimulus produces freckles and other diseases of the skin. (3) On the functions of the nervous centres. The influence in moderation is wholesome; in excess produces excitement, pain, or even delirium and death by sun-stroke; lunar influence on maniacs. (4) On the general health, as indicated by liability to disease and by the rate of mortality under the operation of disease. (See Carpenter, loc. cit. § 95.) On the whole subject of the influence of light as a vital stimulus. See Ibid. g T9 to I 97. SYLLABI'.-!, ErlY. (b) ON HEAT, AS A CONDITION OF VITAL ACTIVITY. 270. Notice of the influence of heat as an exciting cause of mechanical and chemical changes. Its influence on vegetation on a large scale, exhibited in the changes produced by summer and winter and confirmed by the experiment of artificially inverting the seasons. Geographical distribution of plants at different distances from the equator, and precisely parallel phenomena at different alti- tudes above the level of the sea at the same latitude. Explanation of the effect of excessive heat in destroying life. Too consider- able an abstraction of heat may produce the same result by effect- ing some mechanical change inconsistent with vital action, or else it may merely suspend without destroying the power of vital action, producing the phenomenon of dormant vitality. 271. Influence of heat on the actions of animals. Distinction between warm and cold-blooded animals, as to the range of bodily and external temperature compatible with vital activity and the retention of vital power. Hence cold-blooded animals best ex- emplify the influence of this agent on the different functions; (1) nutritive functions; (2) on respiration and circulation; (3) ner- vous functions; (4) motorial power; (5) functions of the skin. See Carpenter, loc. cit. § 97 to § 141. For a notice of other external conditions of vital activity, such as Electricity, Moisture,