The following are instances of this singular class of animals:-The sea nettle, polypus, hydra, coral, and sponge. The name zoophyte is derived from two Greek words, wv (zoon), an animal; puro (phyton), a plant; while that of radiata, derived from the Latin, evidently points out the radiated or ray-like arrangement of their parts.

"Before my time," says the Baron Cuvier in a note to his first edition, "modern naturalists divided all Invertebrated Animals into two classes-Insects and Worms. I was the first who attacked this view of the subject, and proposed another division, in a paper read before the Society of Natural History at Paris, the 21st Floreal, year iii. (or 10th May, 1795), and which was afterwards printed in the "Decade Philosophique." In this paper, I pointed out the characters and limits of the Mollusca, the Crustacea, the Insects, the Worms, the Echinodermata, and the Zoophytes. The redblooded worms, or Annelides, were not distinguished until a later period, in a paper read before the Institute, on the 11th Nivose, year x. (or 31st December, 1801.) I afterwards distributed these several classes into three grand divisions, analogous to that of the Animalia Vertebrata, in a paper read before the Institute in July 1812, and afterwards published in the Annales du mus. d'Histoire Nat. tome xix."

WHEN we contemplate the face of the earth, we perceive it to be covered with living beings. Animals and plants are to be found in every corner of the globe, with the exception of the poles, where perpetual frosts and the long darkness of winter render the land incapable of supporting them; and where, to use the words of the poet, "Life itself goes out." We even find the remains of living bodies at enormous depths below the surface, in spots which once formed the beds of run ning streams, or the bottom of a mighty ocean, from which situations they have been elevated by the ordinary laws of volcanic agency. The mould forming the surface of the earth is composed of the remains of generations which are now no more: it serves to maintain the growth of living plants, and, through them, of all living animals. In the atmosphere surrounding the globe, every thing is fitted for life: light and heat bring organized bodies into existence; the air, covering the earth in every direction to the depth of many leagues, continually exchanges its particles with those of living bodies. Finally, water, which passes incessantly from the sea to the clouds, and from the clouds to the sea, is another element essential to life.

Life is one of those mysterious and unknown secondary causes, to which we assign a certain series of observed phenomena, possessing mutual relations, and succeeding each other in a constant order. It is true that we are completely ignorant of the link which unites these phenomena, but we are sensible that a connexion must exist; and this conviction is sufficient to induce us to assign to them one general name, which is used in two senses: first, as the sign of a particular principle; and, secondly, as indicating the totality of the phenomena which have given rise to its adoption. As the human body, the bodies of the other animals, and of plants, appear to resist, during a certain time, the laws which govern inanimate bodies, and even to act on all around them in a manner opposed altogether to those laws, we employ the terms Life and Vital Principle to designate these apparent exceptions to general laws. It is, therefore, by determining exactly in what these exceptions consist, that we shall be able to understand clearly the meaning of those terms. For this purpose, let us consider living bodies in their active and passive relations to the rest of nature.

For example, let us contemplate a female in the prime of youth and health. The elegant form, the graceful flexibility of motion, the gentle warmth, the cheeks crimsoned with the blushes of beauty, the brilliant eyes sparkling with the fire of genius, or animated with the sallies of wit, seem united to form a most fascinating being. A moment is sufficient to destroy the illusion. Motion and sense often cease without any apparent cause. The body loses its heat, the muscles become flat, and the angular prominences of the bones appear; the cornea of the eye loses its brightness, and the eyes sink. These are, however, but the preludes of changes still more horrible. The neck and abdomen become discoloured, the cuticle separates from the skin, which becomes successively blue, green, and black. The corpse slowly dissolves, a part combining with the atmosphere, a part reduced to the liquid state, and a part mouldering in the earth. In a word, after a few short days there remain only a small number of earthy and saline principles. The other elements are dispersed in air and water, prepared again to enter into new combinations, and to become the constituent particles, perhaps, of another human body.

It is evident that this separation is the natural effect of the action of the air, heat, and moisture;

in a word, of external matter upon the dead animal body; and that its cause is to be found in the elective attraction of these different agents for the elements of which the body is composed. That body, however, was equally surrounded by those agents while living, their affinities for its molecules were the same, and the latter would have yielded in the same manner during life, had not their cohesion been preserved by a power superior to those affinities, and which never ceased to act until the moment of death.

All living beings are found to possess one common character, whatever differences may prevail among them. They are all born from bodies similar to themselves, and grow by attracting the surrounding particles which they assimilate with their substance. All are formed with different parts, which we call organs, and from which they derive the appellation of organized beings. These organs united together form a whole, which is a perfect unity in respect to form, duration, and the phenomena it exhibits; and, as one of these properties cannot be abstracted from the rest without annihilating the whole, a living being receives the name of individual. Each being possesses a degree of heat, differing in different beings, and, to a certain point, independent of surrounding bodies. They all resist the laws of affinity which sway the mineral kingdom, and the compositions which they form are submitted to laws different from those influencing the mixtures of the chemist. They all absorb something from without, and transform it within; and all exhale certain principles, the product of the vital action. All reproduce other and similar beings, by the same actions by which they were themselves produced. All exist for a time, variable for each individual, but nearly the same for the same species, when in the wild state of nature. After this active individual existence, they all cease to live; and, finally, their bodies are dissipated into their more simple elements, according to the universal laws of Inorganic Chemistry.

Thus every living being forms, by its unity, a little world within itself; yet this little world cannot remain isolated from the universe without. In life, there is always a bond of mutual dependence among the organs-a universal concourse and agreement of actions. Every part corresponds with the whole, and the whole with the universe.

If, then, we wish to distinguish a living body from another organized body, but without life, we have only to ascertain whether it continue to interchange particles with the soil, or gaseous fluids, which surround it; or. on the contrary, whether it maintain no active or efficacious relations with the universe. Again, if we wish to distinguish an organized body, which has ceased to live, from a mineral, we have only to ascertain whether the particles are otherwise united than by the ordinary molecular attractions, and whether the free action of the elements is about to annihilate it either by destruction or putrefaction.

The division of Living Beings into Animals and Plants has been already explained. The former, being of a complex nature, are provided with an internal cavity which receives their aliment, and are endowed with sense and spontaneous motion. Directed by instinct, they are alike capable of avoiding injury, and of pursuing their natural good. The latter, fixed to the earth by their roots, and deprived of the faculties of sensation and motion, are placed by Nature in situations fitted to supply their wants. The materials necessary for their sustenance are absorbed directly, without instinct or motion, and are abundantly supplied without either preparation or complicated labour. Animals, endowed with the distinctions of sex, both of which sometimes co-exist in the same individual, but more frequently in separate individuals of the same species, preserve these distinctions during the whole period of their lives. Almost all plants, on the contrary, have the two sexes united in the same being; and the distinctive characters of sex are lost and renewed every year. Again, the internal structure of animals is more complicated than that of plants: it is internally that the great functions of life are performed. With plants, on the contrary, the principal organs are placed on the surface; and their functions are mostly performed externally. As soon as an animal is born, its organs are exhibited: they require nothing but development and growth to form a perfect animal; and, if we except certain metamorphoses, the external form of the adult is already sketched. The vegetable, born from a seed, develops its organs successively; first the root, then the stalk, leaves, and flowers;—and when the flowers have bloomed, they die; the rest of the organs perish, the whole ceases to live, or sometimes only the stalk, or perhaps only the leaves. Not a year elapses but each flower is destroyed or renewed, partially or entirely. Thus, the two classes of beings possess in common the powers of nutrition and of reproduction. The animal has, however, something more than the vegetable, and enjoys the higher powers of sensation and voluntary motion. The animal alone possesses nerves, muscles, blood, and some kind of stomach. One at least of these organs is always visible; and, as the nerves and muscles are intermittent in their action, and incapable of maintaining a long-continued exercise without repose, animals possess a new distinctive mark in that periodical sleep to which they are at intervals subjected.

To a person who has considered Life only in Man, or in those higher animals which most resemble him, it appears almost superfluous to explain the essential difference between an animal and a plant. If there existed upon the face of the earth only such animals as birds, fishes, or quadrupeds, there would then be no occasion to enlarge so fully upon the distinctions in their functions: the

line drawn by the hand of Nature would suffice. We should readily be preserved from error on this point by their senses, their voluntary motion, the symmetry and complexity of their structure, but, above all, by the instinct which directs their actions. Then we might say with Linnæus, Vegetabilia crescunt et vivunt; Animalia crescunt, vivunt et sentiunt" (Vegetables grow and live; Animals grow, live, and feel); and this definition would be as accurate as it is brief. We should not be obliged to separate Corals, Polypi, Insects, Crustacea, and Symmetrical Shells, from the Vegetable Kingdom. But such is not the case. All animals do not exhibit the distinctive marks of complicated structure and voluntary motion. This may be easily inferred from the fact, that Tournefort, a man of great talents, and an able naturalist, actually formed nine genera in the seventeenth family of his Botanical system with those Polypi which were known to him and to his learned contemporaries. At a later period, Trembley hesitated for a long time before he could determine whether the Hydra was an animal or a plant; and the experiments which he performed to determine the question have been admired by all the philosophers of his time. The dexterous manipulations of Trembley are the more remarkable, as Peyssonel had previously observed that minute animals inhabit the different compartments of the corals. This discovery was extended by Ellis and Solander to all kinds of Polypi; while Donati, Réaumur, and B. de Jussieu, brought the subject prominently forward in their public lectures and writings. The question, however, still remained in an unsatisfactory state, and attracted the attention of the distinguished naturalists of the eighteenth century. Buffon proposed to establish an intermediate class between animals and plants. Linnæus adopted this suggestion, although it proceeded from Buffon; and rendered the distinction permanent by the title of Zoophytes, or Animated Plants. The celebrated Pallas followed Linnæus; Cuvier adopted the word and the distinction; while Lamarck rejected them both.

These doubts and differences of opinion among enlightened men could only have proceeded from the obscurity of the subject. One cause of the obscurity arose from the false direction which their studies had unfortunately taken. Confining themselves to their cabinets, naturalists remained too far from Nature. They had found solid bodies-Corals, Sponges, Alcyonia, Polypi, of innumerable shapes, sometimes covered with soft and moveable bodies, and sometimes without them. Instead of considering the soft body as the artificer of the solid mass, they believed that the latter produced the former; and as the solid masses were observed to grow and vegetate, they were hastily considered to be plants, while the soft bodies were regarded as the flowers of these extraordinary vege tables. The error was farther confirmed by the circumstance, that at the particular period when these Polypi reproduce other beings of the same species, their bodies are covered with little buds and shoots, which bear a great resemblance to certain flowers, the structure of which cannot be very distinctly perceived. But when these supposed flowers were observed to be endowed with spontane ous motion, and that they were possessed of sensation, a great difficulty arose; and the name of Zoanthes, or animated flowers, was assigned to them.

It has now, however, been completely ascertained that the Polypi themselves fabricate these solid apparent vegetables, which serve for their abodes. They secrete them in very nearly the same manner as the Mollusca form their shells; the Teredo its testaceous tube; the Lobster its crustaceous envelop; the Tortoise its shield; the fishes their scales; insects their elytra or wing-cases; birds their plumage; the Armadillo his scaly covering; the whales their horny lamina; quadrupeds ¦ their skins and organs of defence; and Man, his hair, nails, and cuticle. In all these beings there are to be found some parts which vegetate; and if it were necessary to class with plants all beings which are found to vegetate in any of their parts, we ought, consistently, to include all the animals just named with Zoophytes or animated plants of Linnæus and Pallas.

The following are the characters by which we may always ascertain whether a living being, organized, growing, drawing in nutriment, possessing an internal temperature peculiar to itself, and reproducing its kind, be an Animal or a Plant.

If it be irritable to the touch, and moves spontaneously to satisfy its wants,-if it be not deeply rooted in the soil, but only adhere to the surface,-if its body be provided with a central cavity,if it putrefy after death,-if it give out the ammoniacal odour of burnt horn,-and finally, if in its chemical composition there be found an excess of azote over carbon,-then we may be certain that it is an Animal. But if, on the contrary, the doubtful being under examination enjoy no lasting or spontaneous power of motion,-if it be destitute of an internal cavity,-if it be deeply inserted in the soil,-if, when detached, it speedily fade and die,-if, when dead, it merely ferment, but do not putrify, if it burn without the odour of a burnt quill or horn,—and if its residue be very considerable and chiefly carbon,-then we may venture to declare it to be a Plant.

These characters are sufficient, and can, in general, be easily ascertained. In this enumeration, no allusion has been made to sensation as a distinctive mark of the two classes of living beings; because, in the lowest classes of animals, where alone any difficulty can arise, it is only from the property of irritability that we can infer sensation. The phenomena of reproduction have likewise not been alluded to, because it is in the lowest animals, which we are the most likely to confound

with plants, that this power is still involved in great obscurity, or altogether unknown. It is not, as we might at first sight suppose, the most perfect, or, to speak more correctly, the most complicated plants that are likely to be mistaken for animals. A moment's reflection will readily show how utterly impossible it is to confound a plant, bearing leaves and flowers, with any animal whatever. But it is otherwise with the less characterized beings; and the Animal and Vegetable Kingdoms may be compared to two mighty pyramids, which touch each other by their bases, while their opposite vertices diverge to two infinitely remote points in either direction.

We have thus shown how extremely difficult it is to characterize the essential differences of animals and plants in one short definition. Even Cuvier himself, who spent twenty years of his life in examining the organization of animals, from the simple Polypus up to Man, has carefully abstained from proposing any such definition.

This difficulty increases in proportion to the number of animals under examination. It does not consist in ascertaining the characters appropriated to particular animals, but in selecting such a trait as shall be common to them all. We know that none but animals are possessed of a brain, nerves, muscles, heart, lungs, stomach, or skeleton. We know that they alone move, digest, respire; that they alone have blood, and seem to feel;-but the point is to ascertain which of these characters remains throughout the vast chain of beings, and which of them can be traced in the last link as well as in the first. We see the lungs disappear, then successively the glands, the brain, the skeleton, the heart, the gills, the blood, the nerves, the muscles, and finally, even the vessels; while in the lowest animals of all, we can scarcely ascertain whether they possess a digestive cavity or a stomach. However, as we find this last-mentioned organ in almost all animals, and as it can be clearly observed even in those which have no other externally visible organ, we may reasonably conclude that it is to be found in all; and, if we fail to discover a stomach in many, we should rather suppose our failure to proceed from want of skill, or from want of sufficient delicacy in our senses, arising probably from the excessive minuteness of the beings under examination. We shall, therefore, assume that all animals possess a stomach, and that they digest; we may infer that they are all possessed of sensation; but it is absolutely certain that they all, and they alone, permanently possess the power of voluntary motion.

If, therefore, we may venture to propose a definition which shall be generally applicable to all animals, we should define them to be Living Beings having stomachs. The stomach is, in fact, the great essential spring of every animated being. Nerves and muscles, organs of sensation and motion, appear indeed to be of a higher and more elevated character than the organ of digestion. Yet would these golden wheels of animated nature be inert and motionless, if they were not influenced by this prime-mover, formed of a coarser, but more energetic material, which supplies the fuel to their fires, and enables them to maintain undiminished the original vigour of their motions.

SECT. X.-GENERAL REVIEW OF LIVING BEINGS CONTINUED.

Their Unity and Perfection-Symmetry-Mutual Dependence-Classification of Living Beings. ALL living beings are organized; that is, they are composed of different organs, each performing its separate function, and in its own peculiar manner. These organs collectively form a whole, perfect in each being; and the aggregation of those actions compose all that we are permitted to know of Life. Without the healthy state of the body, life cannot exist; yet the organs remain after life has ceased. We behold a body, which has just been deserted by the breath of life; we perceive an exquisite machine, where nothing seems defective; the wheel-work remains entire, but it wants the propelling hand of the workman. We may admire the sublime mechanism of that mighty Being who formed it, but the moving power ever escapes our research.

The greater number of living beings possess numerous organs, and a complicated structure. When the functions are various, the structure becomes intricate; but there exists a regular gradation-a well-marked hierarchy of functions, as well as of organs. All living bodies absorb nutriment, and reproduce their species; all animals move spontaneously at least some of their parts; many visibly respire; Man thinks. But it is evident that the first order of these functions is nutrition-the other phenomena always presuppose this one. Let us, then, examine the subject of nutrition, and we shall assuredly commence at the first link in the vital chain.

The greater number of Plants have a root fixed in the earth, a stem which shoots into the air, and directs itself towards the light. This stem bears leaves, branches, and flowers; these flowers, of various degrees of complication, produce fruits or seeds, destined to form a succession of beings, similar to those which have produced them. If we desire to ascertain which of these organs is

essential to the existence of the plant, and, with this view, we successively abstract these several parts; if we cut off the fruits and seeds, the remainder of the plant rests uninjured. The stalk may lose its leaves without perishing; it may be cut, and the roots will continue to live and absorb in their ordinary manner-nay, the root will often even reproduce parts similar to those of which it has been deprived. The root is, therefore, the most important part of the plant, and by it principally the whole vegetable is nourished.

Something similar to this may be observed in Animals. We see an animal of a very complicated structure. A bony skeleton, nerves, organs of sensation, a brain, muscles for motion, a heart for circulating the blood, lungs for absorbing air, a stomach in which the nutriment is deposited and prepared, glands for secreting the humours, arrangements for continuing the species, a general covering for protecting the whole, and limbs for changing its situation;-all these organs, and many more, compose its substance. In beings of this degree of complication, it is impossible to assign to each organ its proper degree of importance, because we cannot abstract any without injuring them all; and many cannot even be touched without subverting the entire fabric. But this separation, which we should in vain attempt to perform, Nature has herself realized in the long chain of animated existence. In descending from the viviparous quadrupeds to the birds, from the birds to the reptiles and fishes, and passing from the birds and fishes, by the mollusca and insects, to the worms and polypi, we see these living machines become more simple, until at length we find, in the lowest orders, nothing but that first principle indispensable to all animals. The whole body of the polypus forms, in fact, nothing but one entire stomach, without any other perceptible organ; and this alone is essential to the existence of a being so extremely simple.

We may thus conclude, that as the root is the first and essential element of the plant, so the stomach is the foundation of animal organization. Nature confirms this principle throughout all her works. She has created vegetables which are composed entirely of one vast root, and has formed animals of a simple gelatinous mass, containing only one enormous stomach. All the functions are, however, of an extreme simplicity in bodies so homogeneous. In order that a vegetable may exist, composed entirely of a root, it is necessary that the substances proper to be absorbed should surround this root; it must be attached to a soil, composed of mould, and saturated with moisture, or to another plant; and these conditions are sufficient for its individual existence. As it produces no flowers, the species can only be continued by off-sets, buds, artificial or natural divisions of the root; and it is chiefly in this way that such bodies are propagated. But that an animal-polypus or worm- -composed of one entire stomach, may exist, different arrangements are requisite. The stomach is placed internally; therefore, it is evident that the food must be carried into it. The animal must be able to move towards the food, and to draw it, by certain partial movements, within the cavity. In order to seek its food, it must feel and perceive; while a certain degree of instinct must exist, that it may adopt these movements, in proportion to its wants. Thus, from one fundamental arrangement, there arises a being, perfect though simple, but which, though simplest of its kind, already appears complicated.

Al

We have styled the polypus a simple being, because it is composed of one entire stomach. though it moves, and must feel, we can perceive no muscles, brain, or nerves; it possesses powers, while the intruments remain concealed. Yet the polypus must be considered as a perfect being, because to it is assigned all the conditions necessary for its continued existence: it is in this respect as perfect as a bird, or as one of the Mammalia. It is true that the animal possesses neither a heart nor lungs, no vessels or glands; but it has no occasion for them. When the body is one entire stomach, and when the animal is perfectly simple and homogeneous throughout, it is evident that these structures would be superfluous. Organs are only necessary when circulation and respiration are confined to particular parts. Every portion of the animal can draw from the alimentary canal that part of the nutriment necessary for its sustenance: it can breathe and assimilate these particles into its proper substance. But when the animal is not possessed of this perfect homogeneity throughout, it then becomes necessary that it should have a proper stomach to receive the nutriment, a heart to distribute it along with the blood into all the organs, and gills or lungs to purify this nutriment by exposure to the air. Unity of action is a first principle in life; and, in the higher orders of animals, it is the heart and the lungs which produce this unity in respect to nutrition, in the same manner as the brain realizes the unity of sensation.

Organization may exist without life, as living bodies are subject to death; but whoever says Life, also says Organization. Buffon was therefore guilty of a pleonasm, when he defined animals to be— Bodies, living and organized.

This organization of living bodies is regulated by certain fixed rules, which have received the name of laws from their constancy and universality. We have just spoken of the perfection and unity observable in all living bodies. The latter, however, is not absolute. Animals possessing a complicated structure are in truth individuals; but with plants and with the lower animals individuals cannot be strictly said to exist, at least in the sense in which the term is understood in regard to Man and the higher animals. It is true that, as long as the several organs remain untouched,