– f'. ETTTTTTTTW º fººd in...sº ºr the tNIVERSITYºu'lliºn É | C H :--- | t..º - º º .3% * * . - iº .N hº... - # . . . . * st G - —º | S - . “wº a - . . . $º º * - * * Rºsº º - - - Pt. NiMSU L Aº ~ - -- * = -:F. * , * --> - --- - - - - : —- . . . -> - - - . … ---. 5" . . º.º. " J. & S *2. THE PHILOSOPHY OF NATURAL HISTORY, BY WILLIAM SMELLIE, Member of the Antiquarian and Royal Societies of Edinburgh. WITH AN' INTRODUCTION AND VARIOUS ADDITIONS AND ALTERATIONS, INTENIDED TO ADAPT IT TO THE PRESENT STATE OF KNOWLEDGE, BY JOHN WARE, M. D. THIRD EDITION. -º- BOSTON : HILLIAR D, G RAY, LITTLE, AND WILKINS. 1829. DISTRICT OF MASSACHUSETTS, To wrt : District Clerk’s Office. BE IT REMEMBERED, that on the seventh day of January, A. D., 1824, in the fortyeighth year of the Independence of the United States of America, Cummings, Hilliard, & Co. of the said dis- trict, have deposited in this office the title of a book, the right whereof they claim as Proprietors, in the words following, to wit: “The Philosophy of Natural History, by William Smellie, Member of the Antiquarian and Royal Societies of Edinburgh. ... With an Introduction and various Additions and Alterations, intended to adapt it to the present State of Knowledge. By John Ware, M. D. Fellow of the Massachusetts Medical Society, and of the American Academy of Arts and Sciences.” In conformity to the Act of the Congress of the United States, entitled, “An Act for the encour- agement of learning, by securing the copies of maps, charts, and books, to the authors and proprietors of such copies, during the times therein mentioned :” and also to an Act, entitled, “An Act, sup- plementary to an Act, entitled, “An Act for the encouragement of learning, by securing the copies of maps, charts, and books, to the authors and proprietors of such copies, during the times therein mentioned ;’ and extending the benefits thereof to the arts of designing, engraving, and etching his- torical and other prints.” JNO. W. DAVIS, Clerk of the District of JMassachusetts. EXTRACT FROM THE PREFACE TO THE ORIGINAL WORK. ABout fifteen years ago, in a conversation with the late' worthy, respectable, and ingenious Lord KAMEs, upon the too general neglect of natural knowledge, his Lordship suggested the idea of composing a book on the PHILosophy of NATURAL. History. In a work of this kind, he proposed that the productions of Nature, which to us are almost infinite, should, instead of being treated of individually, be arranged under general heads; that, in each of these divisions, the known facts, as well as reasonings, should be collected and methodised in the form of regular dis- courses; that as few technical terms as possible should be employed ; and that all the useful and amusing views aris- ing from the different subjects should be exhibited in such a manner as to convey both pleasure and information. This task his Lordship was pleased to think me not alto- gether unqualified to attempt. The idea struck me. I thought that a work of this kind, if executed even with moderate abilities, might excite a taste for examining the various objects which everywhere solicit our attenition. A habit of observation refines our feelings. It is a source of interesting amusement, prevents idle or vicious propensi- ties, and exalts the mind to a love of virtue and of rational entertainment. I likewise reflected, that men of learning often betray an ignorance on the most common subjects of Natural History, which it is painful to remark. iv I have been occasionally employed, since the period which I have mentioned, in collecting and digesting ma- terials from the most authentic sources. These materials I'have interspersed with such observations, reflections, and reasonings, as occurred to me from considering the multi- farious subjects of which I have ventured to treat. I knew that a deliberate perusal of the numerous writers from Aristotle downwards, would require a considerable portion of time. But the avocations of business, and the trans- lating of a work so voluminous as the Natural History of the Count DE BUFFON, rendered my progress much slower than I wished. I now, however, with much diffidence, submit my labors to public opinion. With regard to the manner of writing, it is perhaps im- possible for a North Briton, in a work of any extent, to avoid what are called Scotticisms. But I have endeavour- ed to be everywhere perspicuous, and to shun every sen- timent or expression which might have a tendency to injure the feelings of individuals. Indulgent readers, though they must perceive errors and imperfections, will naturally make some allowance for the variety of research, and the labor of condensing so much matter into so small a compass. He is a bad author, it has been said, who affords neither an aphorism nor a motto. Upon the whole, the general design of this publication, is, to convey to the minds of youth, and of such as may have paid little attention to the study of Nature, a species of knowledge which it is not difficult to acquire. This knowledge will be a perpetual and inexhaustible source of many pleasures; it will afford innocent and virtuous amusement, and will occupy agreeably the leisure or vacant hours of life, ADWERTISEMENT TO THE FIRST EDITION. IN preparing this edition of Smellie's Philosophy of Nat- ural History, I have endeavoured to avail myself of such moderm discoveries and improvements in Physiology and Natural History as are connected with the subjects of which the book treats. It will be observed that instead of the two first chapters of the original work, I have substituted an Introduction, containing some very general views of animal and vegetable life, and a brief sketch of the struc- ture and classification of the whole animal kingdom. That something of this kind was rendered necessary on account of the light thrown upon these subjects by the progress recently made in Comparative Anatomy, cannot be doubt- ed; and it was found easier to compose these chapters entirely anew, than to incorporate the requisite additions with them as they originally stood. With regard to the remainder of the work, although a good deal has been added or rewritten, yet it has upon the whole been made considerably shorter, by the omission of many passages, which did not seem of sufficient import- ance to be retained; and also by the omission of many passages and a few chapters which touch upon subjects interesting only to the scientific reader, and which were deemed unnecessary in an edition intended for general use. Some apology may perhaps be required for the #. with which these alterations have been made in a standard vi work of so great merit. On this subject it can only be said, that there was no other method by which it could be adapted to the use of young persons learning the elements of Natural History. Some of the views contained in the original edition have been since proved unfounded, and these it was necessary to correct. In some parts of it are details of great length, and often irrelevant to the subject, which it was thought proper to abridge or exclude ; and I trust that, upon a fair comparison of it with this edition, I shall appear to have taken no greater liberties than were necessary to fit it for the purpose for which it is principally intended—the instruction of the young. The whole Introduction, as was observed above, has been prepared by the editor, with the exception of few passages, distinguished by inverted commas, which are re- tained from the original work. In the body of the book, those passages which have been added, or which have been entirely remodelled or rewritten, are distinguished by single inverted commas; quotations from other authors being marked in the usual way by double inverted commas. Boston, Jam. 1824. J. W. IN the Second and Third Editions no alterations, except of a merely verbal nature, have been made. Boston, Sept. 1829. J. W. CONTENTS. INTR. ODUCTION. CHAPTER I. Of the Nature of Living Bodies and the Distinction between Animals and Vegetables - - - - - 1–12 CHAPTER II. General Remarks on the Structure of Vegetables - - - - - 12–15 CHAPTER III. Of the Structure of Animals - - 15–84 gºººººººººº. PHILOSOPHY OF NATURAL HISTORY. CHAPTER I. Of Respiration - - - - 85–99 CHAPTER II. Of the Motions of Animals tº 100–108 CHAPTER III. Of Instinct - - - - - 109–116 CHAPTER IV. Of the Senses - - - - 117–134 CHAPTER V. Of Infancy - - - - - 134–141 CHAPTER VI. Of the Growth and Food of Animals 141–154 CHAPTER VII. Of the Transformation of Animals 154–168 CHAPTER VIII. Of the Habitations of Animals – 168–209 CHAPTER IX. Of the Hostilities of Animals - 209–227 CHAPTER X. Of the Artifices of Animals - 227—237 CHAPTER XI. Of the Society of Animals - - 238–250 CHAPTER XII. Of the Docility of Animals - 250–269 viii CHAPTER XIII. Of the Covering, Migration, and * Torpidity of Animals - – 269–293 CHAPTER XIV. Of the Longevity and Dissolution of Organized Bodies - - - 293–306 CHAPTER XV. Of the Progressive Scale or Chain of Beings in the Universe - 307–311 Analytical Table of Contents - - - - - 313–321 Explanation of Scientific Terms - - - - 323–327 THE PHILOSOPHY OF * N A T U R A L H IS TO R Y. • INTRODUCTION. CHAPTER. I. of THE NATURE OF LIVING BODIES, AND OF THE DISTINCTION BETWEEN ANIMALS AND VEGETABLES. THE most superficial observers are in the habit of remark- ing certain great and striking differences in the nature, structure, and qualities of the objects around them. They perceive at once, that a stone is something very different from a plant, and a plant something very different from an animal, although they do not task themselves to determine exactly in what the difference consists. It is natural as well as convenient, for mankind to class things together according to their most obvious characteristics, and in this way we have come into the use of a certain arrangement of natural bodies, not founded upon a knowledge of their intimate nature and essential properties, but upon those qualities which produce the most lively impression on our senses after only a slight examination. Thus have been established the mineral, vege- table, and animal kingdoms, which include under them all the objects of the material world. It is obvious that this arrangement is founded upon an ex- amination of those objects only, which are most within our immediate observation, and with whose qualities and proper- ties we have been most familiar. We see that rocks and mountains are immoveably fixed to the same spot, and remain always of the same size; that the earth does not change its surface except by the operation of violent and unusual causes. 1 2 NATURE OF LIVING BODIES. Plants, on the contrary, are undergoing constant and sponta- neous changes; some are dying and decaying, whilst others are sprouting up from the earth, coming forth, as it were, from a new creation, giving birth to a new set of individuals like themselves, and sinking in their turn to decay. Further still, we see animals, not only coming into existence, living, growing, and giving origin to other animals, but exercising various other offices; feeling, moving, uttering sounds, suf- fering and enjoying, establishing a thousand connexions with things and beings about them, which contribute to the sup- port or happiness of their existence. In this way we have come to the division of created things into the three classes above mentioned. It is sufficient and convenient for the po- pular purposes to which it has been usually applied, but it is evident, if we but examine it, that it is not strictly and scien- tifically correct. A more accurate and philosophical division of natural ob- jects is into such as are possessed of life, and such as are not possessed of life. This throws animals and vegetables into one class, and all mineral substances into the other; for there is a much more close and intimate relation between the two former, than there is between either of them and the latter. They have many circumstances of analogy with one another in respect to their structure and functions, in which they do not at all resemble any object or operation of the mineral kingdom. These two classes, then, include all the various bodies which compose the world around us, and those be- longing to each are distinguished as possessing certain gene- ral properties and being governed by certain general laws, common, in a greater or less degree, to all of the same class. In the first place, living bodies are distinguished from other substances in the mode of their origin ; they are always pro- duced by other preceding individuals similar to themselves; they are always the offspring of parents. This is an obvious and complete distinction. No mineral substance, no 'sub- stance not possessed of life, is ever brought into existence in this way. It is true, that new bodies in the mineral world are sometimes formed by the accidental aggregation of par- ticles, or by the spontaneous combinations which are occa- sionally the result of chemical laws; but this is clearly some- thing very different from the mode of production which takes place in living bodies. One stone does not produce another like itself, a crystal does not produce a crystal, nor one grain of sand another. There is nothing like the relation of pa- rent and offspring. NATURE OF LIVING B ODIES. 3 º In the second place, living bodies differ as to the mode of their existence, in so much as they are dependant upon other things beside themselves for the continuance of that existence. The matter of which they are composed, is constantly chang- ing. This matter is, in fact, only common matter endowed for a certain period with the powers of life, in consequence of being united to living systems. By the various internal ope- rations constantly going on, part of this matter is expended, is sent out of the system ; this loss must be repaired by the addition of new matter. Hence the necessity of nourishment to the support of life ; hence the necessity of a regular sup- ply, to every thing living, of a certain quantity of food adapt- ed in kind to the nature of the individual. This food is operat- ed upon by the organs of the animal or vegetable, is assimi- lated to it, and its properties are modified until it becomes fit to make a component part of it. This is nutrition, an es- sential process of living bodies, by which they are enabled to increase in size and strength, to modify the structure of their different parts, and to maintain them in a fit state for perform- ing the offices for which they are designed. Minerals, on the contrary, have no such dependance ; the matter of which they consist is always the same ; they contain within themselves every thing which is essential to their existence, and have, of course, no necessity for nutrition or growth. It is true that these substances sometimes increase in size, as happens with regard to stalactites, the deposition of crystals, and the formation of alluvia. But there is this marked difference be- tween all such instances of growth, and that of animals or ve- getables; that, in the former case, it amounts to the mere juxtaposition of similar particles, unchanged in their nature; whilst in the latter the particles are changed in their nature, and subjected to the operation of entirely new laws. In the former case, the growth depends upon a principle operating from without; in the latter, upon a principle operating from within. § But, in the third place, though dependant upon other sub- stances in this way for the means of continuing their exist- ence, living bodies possess in another point of view a kind of independence upon all other matter. They are removed, by the possession of the powers of life, in a certain degree out of the influence of physical and chemical laws; they contain within themselves a principle by which they are enabled di- rectly to resist the operation of those laws, which would other- wise ensule their speedy destruction. They depend upon * 4. NATUIRE OF LIVING BOI) IES. the things around them for the materials for their support but the power of altering the nature of those materials and appropriating them to their own use, is peculiar to themselves. The functions of living systems are not only performed with- out the assistance of the physical powers of matter, but often in direct opposition to them ; and the substances which are introduced into them, lose their chemical relations, and are combined according to new laws, and for new purposes. This power of insulation, possessed by living systems, is in no instance more strikingly evinced, than in the possession by animals of a certain degree of vital heat, which they pre- serve under all circumstances, short of those which impair or destroy the texture of their parts. This degree of heat— which in man is about 98° of Fahrenheit's thermometer— continues nearly the same, even when we are exposed to the most intense cold, and is but little elevated, when we are sub- jected to a heat above that of boiling water. In many coun- tries, in which the degree of cold is for many months in the year very much below the freezing point of mercury, men not only exist, but enjoy all the comforts of life. In some high latitudes, Europeans have been exposed to temperatures as low as —50° or even —60° of Fahrenheit's thermometer, that is, to a cold 150° below the natural standard of animal heat, and have escaped every ill consequence. Very lately the whole of two ships’ crews wintered in about 75° of north la- titude in perfect safety, where the temperature of the air was, for many weeks together, almost constantly below 30°, and where they became so accustomed to severe cold, that the atmosphere, when at zero, felt mild and comfortable. On the other hand, in many countries men exist without difficulty under a high degree of heat. In Sicily, during certain winds, the thermometer has been observed at 112°, in South Ameri- ca by Humboldt at 115°, in Africa at 125°. But, for a limit- ed period, much higher degrees of artificial heat have been borne without injury. Individuals have exposed themselves voluntarily to the air of ovens at temperatures from 260° to 315° of Fahrenheit's thermometer, without any great incon- venience, while water was boiling and meat baking in the same atmosphere. These facts show a power of resisting the operation of external causes, which is possessed by no sub- stances except such as are endowed with life, and is, proba- bly, possessed in some degree by all that are. For, although vegetables and the lower orders of animals are not capable of resisting to the same extent the influence of heat and cold, NATURE OF LIVING B ODIES. 5 yet they all show, in some measure, the existence of the same power. And in the most imperfect species, where there is no other evidence, this power is evinced by the fact, that the individual freezes with greater difficulty before than after death, other circumstances being equal.” Another illustration of the same principle is derived from the change which takes place in the body after death. With this change we are familiar. No sooner has it taken place, than the heat and moisture of the external air commence the work of destruction. The skin is discolored, it becomes green and livid, the eyes sink in their sockets, the flesh be- comes soft and putrid, it falls from the bones, and is convert- ed partly into foetid exhalations, and turns partly into dust. Even the bones finally yield and lose their form and consist- ency. Now why should this happen more readily after than before death 2 The composition of the body is the same, and it is exposed to the same moisture and heat. It happens be- cause the life has departed which gave to the body a power of resisting the operation of these causes. This suggests to us, in the fourth place, another distinction of living substances, viz. that they all terminate their exist- ence in death. By this event, the materials which entered into their composition are deprived of the bond which held them together and gave to them their peculiar form, viz. the principle of life. They therefore separate, and retain only those properties which they possessed before becoming parts of a living system. Dust returns to dust, earth to earth. It is true, that some of the 'parts of living bodies, both animals and vegetables, do not very readily undergo the process of decay. The bones, teeth, shells, and horns of animals; the trunks, branches, and roots of trees, retain, for an almost in- * In quadrupeds and birds the animal heat is generally greater than that of the surrounding atmosphere, whilst in animals of the inferior classes, it is seldom very different from that of the objects around them. The former are called warm-blood- ed, and the latter cold-blooded. In the former, the temperature is capable of but slight variation, from external causes; in the latter, its range is pretty extensive, and it varies a great number of degrees. The temperature of a man plunged into cold salt water at 44°, has been known to sink to 83°, and, when exposed to a heat- ed atmosphere, to rise to 100°; in other warm-blooded animals similar varieties have been observed. But the temperature of the viper, a cold-blooded animal, when exposed to a heat of 108°, rises to 92°, and when exposed to a cold of 10°, sinks to about the freezing point of water, showing at once an extensive range of tempera- ture within which the functions can go on, and at the same time a decided power of resistance against any further alteration. Eggs possess an analogous power. A new laid egg, and one which has been fro- zen and thawed, being exposed in a freezing mixture together, the former will be some minutes longer in freezing than the latter. This has been ascertained by ex- periment. The same is true of the lower orders of animals and vegetables. 6 DISTINCTION BETWEEN ANIMALS AND VEGETABLES. definite length of time, under certain circumstances, their shape and substance. This, however, is owing, not to their continuing to possess life itself, but to the particular nature and composition of the texture of which they are composed. Nothing like this takes place in other substances; they can be destroyed only by the action of some mechanical agent, which separates their parts, or by that of some chemical one, which alters their combinations. These are circumstances of distinction common to all liv- ing bodies, whether animal or vegetable. But another sub- ject of inquiry is, how are these to be distinguished from each other? Although it may seem very easy to distinguish an animal from a vegetable, yet the true principle of distinction eludes investigation. Many philosophers have attempted to define wherein it consists, but have failed in the attempt. There is generally little practical difficulty in determining whether any particular substance belong to the animal or ve- getable kingdom, and yet so nearly do the lower species of animals resemble plants in the functions they perform, that it is almost impossible to point out what constitutes the real difference between them. - Some writers, among whom was the celebrated Buffon, have believed that there is in fact no exact boundary between the animal and vegetable kingdoms, that they run into each other at their extremities, and form so regular a gradation from the one to the other, that no precise dividing line can be drawn between them. But although there is this apparent confu- sion at the boundaries of the two "kingdoms, yet, generally speaking, animals are distinguished from plants by their com- position, their structure, their mode of life, &c. And although with respect to each particular circumstance there may be particular exceptions, yet, taking the whole together, we get a good general idea of an animal as distinguished from a plant. Thus the power of locomotion, or of motion from place to place, has been considered as peculiar to animals, and in a general way it is so ; yet there are many exceptions. Oysters, the sea anemone, corals, and corallines, now known to be of an animal nature, “can hardly be said to enjoy the power of local motion. Many species remain fixed to the rocks on which they were produced, and have no motion but that of extending and contracting their bodies.” And, on the other hand, some species of plants are not fixed by roots to one and the same spot, but float about in the sea, receiv- ing nourishment from its waters. T) ISTINCTION BET W E EN ANIMA LS AND VEG ETAB L ES. 7 The power of moving some part of themselves by an in- ternal principle has also been believed peculiar to animals. It is not so. Many plants are possessed of the faculty, not only of motion of this kind, but of moving as if with some de- finite purpose. “The sensitive plant possesses it in an emi- nent degree. The slightest touch makes its leaves suddenly shrink, and together with the branch bend down towards the earth. But the moving plant, or Hedysarum gyrans, furnish- es the most astonishing example of vegetable motion. It is a native of the East Indies. Its movements are not excited by the contact of external bodies, but solely by the influence of the sun's rays.” Its motions are confined to the leaves, which are supported by long flexible foot-stalks. When the sun shines, the leaves move briskly in every direction. Their general motion, however, is upward and downward. But they not unfrequently turn almost rolºnd ; and then, their foot- stalks are evidently twisted. These motions go on incessant- ly, as long as the heat of the sun continues. Tºut they cease during the night, and when the weather is cold and cloudy. The Diontea muscipula, or Venus’ flytrap, a plant of Carolina, affords another instance of rapid vegetable motion. Its leaves are jointed, and furnished with two rows of strong prickles. Their surfaces are covered with a number of minute glands, which secrete a sweet liquor, and ałłłire the approach of flies. When these parts are touched by the legs of a fly, the two lobes of the leaf instantly rise up, the rows of prickles lock themselves fast together, and squeeze the unwary animal to death. If a straw or pin be introduced between the lobes, the same motions are excited.” The common barberry (Berberis vulgaris) is another in- stance to the same effect. When its flower is fully expand- ed, if the inside of one of the filaments of its stamens be just touched by a pin or a straw it contracts instantly, and throws its anther forward with some force against the stigma. “When a seed is sown in a reversed position, the young root turns downward to enter the earth, and the stem bends upward into the air. Confine a young stem to an inclined position, and its extremity will soon assume its former per- pendicular direction.” The roots of a free growing on dry or barren ground in the neighbourhood of that which is moist or fertile, become larger, longer, and more full in that direc- tion, than in any other, as if extending themselves to obtain * Sir J. E. Smith asserts that light is not necessary, but that only a warm, still at- mosphere is required to produce this phenomenon in perfection. 8 DISTINCTION BETWEEN ANIMALS AND VEGETABLES. the nourishment which can there be afforded them. If we twist the branch of a tree, so that the under surface of the leaves shall come uppermost, they gradually turn upon their foot-stalk till the proper side is exposed to the rays of the sun. This they will do repeatedly, until they have become injured by the exertion ; and if the leaf be confined, so that it cannot resume its natural position, its stalk will become twisted by the effort to accomplish it. The sunflower, the leaves of the mallow, and some other plants, generally turn their faces towards the sun. The tendrils of plants, on the other hand, move always towards the shade, in whatever di- rection it may be. In a greenhouse, if exposed to the morn- ing light, they direct themselves towards the west, at noon to the north, and at night to the east. They are also attracted by opaque bodies. Instances of a similar nature are afforded by the sleep of plants, as it has been denominated. The leaves of many plants are folded together during the night, and droop as if dying. In some instances they are so arranged, when in this state, as to serve as a cover to the flowers or young fruit, protecting them from the noxious effects of the dew. The flowers of other plants follow the same law, and close at the approach of night, for the apparent object of shelter and pro- tection. The modes in which this is done in different cases are exceeding various, but the simple mention of the fact is sufficient for the purpose of illustrating this internal power of motion. Yet, although we cannot distinctly point out in what this kind of vegetable motion differs from the motions performed by animals, there is no difficulty in perceiving that they are entirely different. Although we see in the vegetable world many instances, where plants exhibit phenomena which seem almost to imply the possession of volition, of sensation, and of thought, yet upon examination of each of these instances, we find ourselves in no danger of confounding the plants, in which they exist, with the animal kingdom. The general as- pect, the form, the structure, and the relation of the various parts, are entirely different; and it is in their general charac- ter that these two classes of created things differ from one another, and not in the possession of any one distinct discrimi- nating principle. Let us look for one moment at the circum- stances in which vegetables and animals are distinguished by the possession of different organs, a different structure, and a difference in the principles which actuate them. IDISTINCTION BETWEEN ANIMALS AND VEG ETABLES. 9 1. With respect to their mode of taking and digesting food. In animals this is done by an act of their own, by the exer- cise of volition. They in some sense exercise choice and make efforts to get that which is adapted to their purposes. This is obvious enough with regard to the larger and more perfect animals; but even in the most imperfect kinds, as in the polypes, we find that they are capable of sending out their arms or feelers in search of food, which, when offered to their grasp, they seize and convey into the organ appropriated for digestion. It is true that the roots and other parts of plants, as has been already remarked, show a sort of intelligence and discrimination in the course which they take in search of moist or fertile ground, and in avoiding or seeking light or shade, which is analogous to the low degree of power mani- fested in the feelers of the polypes ; yet the analogy is but slight, and does not imply the existence of spontaneous and voluntary motion. Animals are affected by the sensation of hunger, and are induced by it to make immediate and volun- tary exertions for its relief. Vegetables are not so affected, and the efforts which they make to obtain nutriment are slow, and accomplished as much by the gradual operation of ex- ternal circumstances, as by an internal and voluntary power. 2. Digestion is performed in animals by means of a stom- ach and an intestinal canal. The food is taken into the body and is there operated upon by organs, which are different in different species, according to the nature of the substances on which they subsist. The principal of these is a stomach. In plants, on the contrary, nourishment is absorbed directly from the earth by the roots, or from the air by the leaves; there is no intermediate organ where a change is wrought in its nature before it is introduced into the circulation ; it is true that it undergoes such a change in order to adapt it to the purposes of the particular plant into which it is taken, yet it is not effected, as in animals, by means of their internal surface. For although it has been said, that the polypes, when turned inside out, continue to perform the function of digestion without interruption as under ordinary circumstan- ces, yet even in this case it is still the internal surface which digests, that which was formerly external, exchanging func- tions as well as situations with that which was within. 3. Animals differ also from vegetables in the nature of their food. They are not capable, like plants, of being nourished by the common elements of nature, but require substances which have been already organized, and have once formed a O 4 alº I 0 DISTINCTION BETWEEN ANIMAT.S AND VEGETABLES. part either of some plant or animal. The polype cannot sub- sist upon the water in which it floats; it cannot thrust its feelers into the soil and draw up nourishment from it like the roots of vegetables; no animal can do it. They must have recourse to either animal or vegetable substances which are adapted to their wants and are thrown in their way. The earthworm, it is true, swallows earth for its nutriment, but only that earth which is full of organized matter in a state of decay, and it is only that matter which is digested, whilst the bare earth is evacuated without alteration. - 4. Animals differ from vegetables in the time of taking their nourishment. The roots of the latter are constantly exposed to the contact of the substances from which they de- rive their support, they are always buried in the earth which contains and from which they absorb their food. Their leaves, also, are always spread to the air from which they receive one portion of their support. It is not so with animals; their supplies of food are only occasional. They are stimulated by appetite, at certain definite periods, to seek for the means of gratifying it; after obtaining which they are engaged by other occupations, and are liberated from this care, until an additional supply becomes necessary, and they are excited to obtain it by a fresh appetite. 5. Animals differ again from plants in being possessed of the powers of feeling and voluntary motion. It is true that very remarkable phenomena are exhibited by individuals of the vegetable kingdom, which seem to imply the possession of these powers. But examination shows a distinction be- tween these instances and those which are afforded by ani- mals. There is not a close resemblance between the con- traction of the leaves of the sensitive plant or the vibratory motions of the Hedysarum gyrans, and the extension of the feelers of the polype or the contraction of the shell of the oyster. The former motions seem to proceed from the actual contact of some substance with the moving part, or from the stimulus of light and heat; the latter, from the spontaneous and voluntary efforts of the animal itself. These differences would be made more obvious by a knowledge of the histo- ry of the lower classes of animals. But it may be at present observed, that however remarkable these instances of vege- table motions are, and although they seem as if they might be the result of knowledge, volition, and sensation, they are yet different in nature from the knowledge, volition, and sen- sation manifested by animals, and do not give cause for con- founding these two classes of beings together. DISTINCTION BETWEEN AN IMALS AND VEGETABLES. 11 6. The structure and form of vegetables afford also marks of distinction. These are sufficiently familiar without any particular explanation. It is true that there are some marine productions, such as the sponges, coral, &c., having the shape and in some measure the appearance of plants, which are yet without doubt of animal origin. But of these it is to be re- marked, that they are not animals themselves, but the resi- dence of animals ; they are substances produced by the labor of myriads of little polypes, who pile them up in order to serve for their covering and habitation ; and although when thus produced they have the external shape of vegetables, the creatures themselves, which have produced them, do not bear the smallest resemblance to plants. 7. The chemical composition of vegetables also differs from that of animals. The elements essential to vegetables are three in number, oxygen, carbon, and hydrogen ; and from these three principally are formed all the different sub- stances which we meet among plants. But besides these, animals require the presence of azote or nitrogen also, which is necessary to their composition ; and from this, combined with the others in different proportions, are formed all the parts absolutely essential to animal existence. There are, it is true, many other elements which are found in some parts of plants or animals, but these are all which are absolutely essential to the composition of vegetable or animal substance. Thus in the bark of some plants, besides the three elements necessary to its formation, there will be found a portion of silex or flint ; and in the bones of animals, in addition to the four essential elements, lime is deposited in large quantities. So that, although there must always be present at least these necessary and specified elements in the composition of vege- tables and animals, there is no limit, no principle which pre- cludes the admission of others. In consequence of this difference in chemical composition, and perhaps of the mode in which the elements are combined, other differences of a particular character may be detected between substances of a vegetable and those of an animal origin ; differences which serve in cases of doubt to assist us in deciding to which class any particular substance belongs. Thus, in burning, substances of animal origin always exhale a very peculiar odor, that of burnt wool, feathers, sponge, &c., an odor easily recognised and not readily forgotten. This will always serve to determine whether any particular substance which we examine, is derived from the vegetable or animal kingdom. 12 STRUCTURE OF VEGETABLES. Physiologists have frequently busied themselves in endea- vouring to discover what it is, which distinguishes precisely the two living kingdoms from each other. They have endea- voured in vain, because they have expected to find this dis- tinction in one single principle which would admit of a short, plain, and specific definition. Such a principle can be only ideal. It does not exist even with regard to the mineral and living classes of substances. It would not be difficult to con- found the boundaries of living and dead matter, in the same way as those of vegetable and animal matter. The distinc- tion must be sought in the general structure, the general mode of existence, and the purposes of existence-in the two. And in a few words we may say, that animals differ from plants in being furnished with internal organs for the pur- pose of digesting food, instead of absorbing it by roots from the earth ; in being furnished with organs which render them capable of moving from place to place, or at least of moving one part of their bodies on some other part; in having pow- ers of sensation, perception, and volition, by which they ac- quire a knowledge of the existence and qualities of other bo- dies besides themselves, and form some sort of relation or connexion with them ; and in being obviously intended, by the possession of these organs and powers, to be conscious of and to enjoy existence. CHAPTER II. GENERAL REMARKS ON THE STRUCTURE OF VEGETABLES. IN considering plants and animals with a view to the des- cription of their structure and organs, there is one remarka- ble circumstance worthy of attention at first, viz. that—while the animal kingdom exhibits a great variety between different classes in respect to the perfection, completeness, and com- plexity of their structure, and the number of their functions; so that a regular series is formed, ascending from the lowest and most imperfect worm possessed of no faculties but those of feeling and moving, up to quadrupeds with all their won- derful and varied powers—the vegetable kingdom, on the con- trary, exhibits but little of this sort of variety. Plants are nearly all alike with regard to the organs they possess and the functions they perform. On the one hand, the polype STRUCTURE OF VEGETABLES. 13 and the elephant do not differ from each other more in size, than they do in the number and complexity of their organs, and the extent and perfection of their powers and functions. Whilst, on the other hand, the humblest moss is scarcely less perfect, less complicated, or possessed of less extensive pow- ers, than the most lofty tree. Vegetables vary in their form, their size, their fruit, and many other particulars; but we cannot say of one, that it is of a higher order in the scale of creation than another, as we can of animals. There is no series beginning at an individual of low and obscure powers, and ending in one of powers numerous and elevated. The structure of plants is exceedingly simple and nearly alike in all the different classes, so far as they have been ex- amined. The important parts, which serve to provide for their nourishment and growth, are the root, the stem, and the leaves. These are all formed of a variety of vessels and tubes, in which the sap and other fluids circulate. The sap is in the first place taken into the roots, probably by means of the long fibrous filaments which are usually extended in every direction, and conveyed into what are called the cen- tral vessels. These are so called from their being arranged, in annual shoots and herbaceous plants, around the pith or centre of the stem. They are constructed of fibres which are wound spirally around them, and are thence sometimes called the spiral vessels. This arrangement probably con- tributes to the motion of the fluids they contain. By these vessels the sap is carried up the stem and distributed to the different branches, and thence to the leaves, flowers, or fruit. In the leaves it circulates and is there exposed to the influ- ence of light, heat, and air; and is no doubt perfected and elaborated by the processes which it undergoes. Returning from the leaves, it descends in a different set of vessels situ- ated in the bark, and in its descent contributes to the growth and nourishment of the plant by depositing new layers of vegetable matter between the bark and the wood. This is the course of the circulation in annual plants, in which there is an entirely pew growth every year from the root. But in trees and shrubs where the same trunk or stem continues from year to year, the arrangement, though essen- tially the same, is a little varied. The central vessels are not situated directly around the pith, but in the external lay- er of wood called the alburnum, which is always the growth of the preceding year, and performs this office only for one season, being afterwards surrounded and enclosed by a new 14 STRUCTURE OF WEGETABLES, layer of the same kind. Hence the trunks of trees are form- ed by layers of wood, which have been yearly deposited around the centre, and have successively afforded a passage for the sap, by means of the central or spiral vessels, to as- cend into the branches and leaves. From the leaves the sap descends through the vessels of the internal layer of the bark, as in the former case, and in its descent gradually contributes to the formation of the alburnum for the next year. That part of the bark, also, which has thus once served the purpos- es of circulation, like the alburnum, is afterwards thrown aside, and its place is supplied by a new layer formed on its inside between it and the alburnum. Hence the large quan- tity of thick and dead bark which is often accumulated upon the outside of the trunk and branches of old trees. This is a slight sketch of some of the most important points in the vegetable circulation. It appears from this, that the principal seat of the growth and nutrition of plants is in the bark and alburnum, and that all the new matter yearly added, is deposited on the outside of the latter and the inside of the former—that the growth of one year is only subservient to the circulation of the next, and is ever afterwards of use mere- ly in giving strength and stability to the trunk, in order to support the increasing size and weight of the branches and leaves. The wisdom and beauty of this provision, by which that portion of the plant, which has become useless for every other purpose, is thus made to answer a very important end, are sufficiently obvious; and it is rendered necessary by the circumstance that plants do not, like animals, arrive at a de- finite size and there cease, but go on growing to an indefi- nite extent, and consequently require corresponding increase of strength in those parts which are to support them. But besides this circulation, which is the most important and interesting part of the vegetable economy, and is also the best understood, the fluids of plants are no doubt subjected in different parts to a variety of operations, and undergo ma- ny changes. There are many other vessels besides those al- ready mentioned, whose office is not perfectly known, but which contribute, probably, in some way, to the elaboration of the different principles found in plants, such as gum, resin, sugar, &c., or are subservient to the performance of their functions. The difficulty of accurately examining the minute structure and organization of vegetables is very great, and it is probable that we shall always remain ignorant of many highly important parts of their physiology. GENERAL CLASSIFICATION OF ANIMALS. 15 It appears from this account, that those parts of plants, which perform the functions necessary to their nutrition and growth, are strictly annual. So that all plants are either an- nual, that is, wholly renewed every year, or at least have the circulating vessels, and all the organs taking an active part in their economy, annually renewed, viz. the alburnum, the bark, the leaves, the flower, &c. This circumstance affords another very obvious general distinction between the vegeta- ble and animal kingdoms ; in the latter, nothing of the kind is to be observed : there is in no case such a renewal of any of the organs of which an animal is composed,—any at least of those concerned in performing important functions. It is true that some of the subordinate parts, such as the hair, the cuticle or scarf skin, the nails, teeth, feathers, &c., are occa- sionally and sometimes annually renewed in certain kinds of animals. But there is no change in any of the principal or- gans; the circulating system, the lungs, the stomach, &c., always remain the same.* The plan of this work does not admit a more full account of the structure, functions, and classification of the vegetable world ; and we proceed therefore to an examination of the animal kingdom. s—-----------------------, ------- — —- CHAPTER III. OF THE STRUCTURE OF ANIMALS. SECTION I. General Classification of Animals. IN order to treat clearly of the animal kingdom, it is ne- cessary to consider it according to some method of arrange- ment, by which those animals that most resemble one another are connected together for the convenience of description. This arrangement is founded upon their form and structure, * It may here be observed, that in vegetables there is none of that absorption of the different parts which takes place in animals. The matter of which they are composed, being once deposited, is never taken up again; whilst in animals there is a constant process going on, by which the old matter is taken away and new de- posited, and the organs thus renewed. Perhaps this end is intended to be an- swered in vegetables by the annual renewing of their circulating system. 16 . GENERAL CLASSIFICATION OF ANIMALS. and separates them into various divisions and subdivisions ac- cording to their degrees of similarity, and the points in which their structures correspond. Such a system of arrangement is called a Classification of the Animal Kingdom ; and as an accurate acquaintance with the principles on which it is founded, is of great assistance to the student of natural histo- ry, I shall proceed to present a general view of that which is most commonly received at the present day.* In surveying the series of animals, from the lowest and most insignificant worm, up to man, the lord of the creation, and examining the structure of their bodies, and the mode in which they are enabled to carry on the functions of life, we observe certain lines of distinction among them, which afford ground for arranging them, in the first place, in two grand divisions. Those of the first grand division are possessed of an internal skeleton, a system of bones covered by the flesh, which serves to give form, support, and strength to their whole fabric, and to assist in containing the various internal organs, whose actions keep up the life and vigor of the system. Those of the second, are not possessed of any such skeleton, but consist of a collection of organs more or less distinct, with- out any solid basis, and are generally of a soft yielding tex- ture, though occasionally covered and protected externally by a shell or other hard covering. We observe farther, that in animals of the first kind, the blood is always red; in those of the second kind, it is, with a few exceptions, white. In those of the first kind, there is always a bony case call- ed the cranium or skull, which contains the brain; and a number of bones called vertebrae, connected together, so as to form a long column, usually called the spine, the back- bone, or the vertebral column. This column contains a ca- nal extending its whole length, which receives the spinal nerve or marrow, as it passes out of the skull, and conveys it along the trunk, to be from thence distributed to the various parts of the body. It is, as it were, the main pillar or com- mon support of all the rest of the skeleton ; and hence the animals possessed of it are called vBNTEBRAL animals, as this forms the most striking characteristic which is compº them all. ->