GENERAL REVIEW OF LIVING BEINGS. 



15 



of actions. Every part corresponcU with tto wtole, and the whole with the uni- 

 verse. 



If, then, we wish to distinguish a Jiving hody from another organised 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 molecu- 

 lar 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 re- 

 ceives 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 arc abundantly supplied without either prepai-ation 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, pre- 

 serve 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 cha- 

 racters of sex are lost and renewed every year. Again, the internal structure of ani- 

 mals is more complicated than that of plants: it is iniemaUy 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 bom, its organs are exhibited: they require nothing but development and 

 growth to form a perfect animal; and, if we except certain metamorphoses, the exter- 

 nal 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 ai-e intermittent in their action, and incapable of maintaining a long- 

 continued exercise without repose, animals possess a new distinctive mark in that pe- 

 riodical sleep to which they arc 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 enlarf^e so 

 fully upon the distinctions in their functions : the line dra»-n by the hand of Nature 

 would suffice. We should readily be preserved from error on this po^nt bv 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 Lin- 

 naeus, " Vegetibilia crescunt et vivunt; Animalia crcscunt, vivunt et sentiunt," (Ve- 

 getables grow and Uve ; Animals grow, live, and feel); and this definition would be as ac- 

 curate 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 preriously observed that mi- 

 nute animals inhabit the different compartments of the corals. This discovery was 

 extended by Ellis and Solander to all kinds of Polypi; while Donati, Reaumur, 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 at- 

 tracted the attention of the distinguished naturalists of the eighteenth century. Buf- 

 fon proposed to establish an intermediate class between animals and plants. Linnaeus 

 adopted this suggestion, although it proceeded from Buffon; and rendered the distinc- 

 tion permanent by the title of Zoophytes, or Animated Plants. The celebrated Pallas 

 followed Linnaeus; Cuvier adopted the word and the distinction; while Lamarck re- 

 jected 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, Naturahsts remained too far from Nature. They had found solid bo- 

 dies—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 for- 

 mer; 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 vegetables. The error was further confirmed by the circumstance, that 

 at the particular period when these Pol)-pi 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 spontaneous 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 fa- 



bricate these solid apparent vegetables, which serve for their abodes. They se- 

 crete them in very nearly the same manner as the Mollusca form their shells ; the 

 Teredo its testaceous tube; the Lobster its crustaceous envelope; the Tortoise its 

 shield ; the Fishes their scales ; Insects their elytra or wing-cases ; Birds their plu- 

 mage; the Armadillo his scaly covering; the Whales their horny lamins; Quadrupeds 

 their skins and organs of defence ; and iMan, 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, wa 

 ought, consistently, to include all the animals just named with the Zoophytes or ani- 

 mated plants of Linnaeus and Pallas. 



The following are the characters by which we may always ascertain whether a liv- 

 ing being, organized, growing, drawing in nutriment, possessing an internal tempera- 

 ture peculiar to itself, and reproducing its kind, be an Animal or a Plant. 



If it be irritable to the touch, and move 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 putrify 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 he 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, bus 

 do not putrify,. — if it burn without the odour of a burnt quill or horn,. — and if its re- 

 sidue be very considerable and chiefly carbon, — then we may venture to declai-e it to 

 be a Plant. 



Tliese 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 irritabiUty that we can infer sensa- 

 tion. 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 comphcated plants that ai-e likely to be mistaken for animals. A moment's re- 

 flection 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 cha- 

 racterized beings ; and the .\nimal 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 dif- 

 ferences of animals and plants in one short definition. Even Cuvier himself, who 

 spent twenty years of his life in examining the organization of animids, from the 

 simple Polypus up to JIan, has carefully abstained from proposing any such defini- 

 tion. 



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 ske- 

 leton. 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 Unk 

 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 final- 

 ly, even the vessels ; whUe 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 fad to discover a stomach in many, we should rather 

 suppose our failure to proceed from want of skill, or from want of sufficient deUcacy 

 in our senses, arising probably from the excessive minuteness of the beings under ex- 

 amination. 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 absolute- 

 ly 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 appli- 

 cable 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 vif our of their 

 motions. 



SECT. X GENERAL REVIEW OF LIVING BEINGS CONTINUED. 



Tlieir Unity and Perfection — Symmetry — Mutual Dependence — Classification of 

 L iv ing'Beinys. 



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 col- 

 lectively 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, Ufe cannot exist; yet the organs remain after life has ceased. We behold a 

 body, which has just been deserted by the breath of hfe; 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 mechamsm of that 

 mighty Being who formed it, but the moving power ever escapes our research. 



