14 



GENERAL REVIEW OF LIVING BEINGS. 



tracting in various ways. In many species earthy lamince or plates, called 

 shells, are secreted from the skin, and their position and manner of 

 production are analogous to those of the mucous bodies. The nervous 

 system is placed within this covering along with the viscera; and the for- 

 mer is composed of numerous scattered masses, connected by nervous 

 filaments. The largest of these masses are placed upon the oesophagus, 

 or gullet, and are distinguished by the term brain. Of the four senses 

 which are confined to particular organs, we can discover traces only of 

 taste and of sight, but the latter is very often found wanting. In only 

 one family, however, there are exhibited the organs of hearing. We al- 

 ways find a complete circulating system, and particular organs for respi- 

 ration. The functions of digestion and of secretion are performed in a 

 manner very nearly as complicated as in the vertebrated animals. 



Animals possessed of this second form are called Molluscous Animals 

 (Animalia mollusca), [from the Latin, mollis, soft.] 



Although the general plan adopted in the organization of their external 

 parts is not so uniform as in the vertebrated animals, yet, in so far as re- 

 gards the internal structure and functions, there is at least an equal de- 

 gree of mutual resemblance. 



The cuttle-fish, oyster, slug, and garden-snail, are familiar instances of this class of 

 animals. 



3. Articulata — Articulated Animals. 



The third form is that which may be observed in Insects and Worms. 

 Their nervous system consists of two long cords, extending the entire 

 length of the intestinal canal, and dilated at intervals by various knots, 

 or ganglions. The first of these knots, placed upon the oesophagus or 

 gullet, and called the brain, is scarcely larger than any of the others, which 

 may be found arranged along the intestinal canal. It communicates with 

 the other ganglions by means of small filaments, or threads, which en- 

 circle the oesophagus like a necklace. The covering of their body is di- 

 vided into a certain number of ring-like segments, by transverse folds, 

 having their integuments sometimes hard, sometimes soft, but always 

 with the muscles attached to the interior of the envelope. Their bodies 

 have frequently articulated limbs attached to the sides, but they are also 

 very frequently without any. 



We shall assign the term Articulated Animals (^Animalia articulata) to 

 denote this numerous division, in which we first observe the transition 

 from the circulating system in cylindrical vessels of the higher animals, to 

 a mere nutrition, by imbibing or sucking in the alimentary substances ; and 

 the corresponding transition, from respiration through particular organs, 

 to one performed by means of trachese, or air cells, dispersed throughout 

 the body. The senses most strongly marked among them are those of 

 taste and sight. One single family exhibits the organ of hearing. The 

 jaws of the Articulated Animals are always lateral, but sometimes they are 

 altogether wanting. 



As instances of this form, we may mention the earth-worm, leech, crabs, lobsters, 

 spiders, beetles, grasshoppers, and flies. From the circumstance of their coverings, or 

 limbs, being divided, or jointed, they derive the name of " articulated," from the Latin 

 articulus, a little joint. 



4. Kadiata — Radiated A7iimals. 

 To the fourth and last form, which includes all the animals commonly 

 called Zoophytes, may be assigned the name of Radiated Animals (Ani- 

 malia radiata.) In all the other classes the organs of motion and of 

 sensation are arranged symmetrically on both sides of a medial line or 

 ■axis ; while the front and back are quite dissimilar. In this class, on the 

 contrary, the organs of motion and of s-ensation are arranged like rays 

 around a centre; and this is the case even when there are but two series, 

 for then both faces are similar. They approach nearly to the uniform 

 structure of plants; and we do not always perceive very distinct traces of 

 a nervous system, nor of distinct organs for sensation. In some we can 

 scarcely find any signs of a circulation. Their organs for respiration are 

 almost always arranged on the external surface of their bodies. The 

 greater number possess, for intestines, a simple bag or sac, with but 

 one entrance; and the lowest families exhibit nothing but a kind of uni- 

 form pulp, endowed only with motion and sensation. 



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, 

 ^o)ov (zoon), an animal; (pvrou {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 IMay 1795), and which was afterwards printed in the ^^ Decade Pliiloso- 

 phique." 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 

 red-blooded 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 Annates du mus. d'Histoire Nat. tome xix,** 



SECT. IX. GENERAL REVIEW OF LIVING BEINGS. 



Life — Animals and Plants — Definition of an Animal. 



When we contemplate the face of the earth, we perceive it to be covered with hving 

 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 ren- 

 der 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 enor- 

 mous depths below the surface, in spots which once formed the beds of running 

 streams, or the bottom of a mighty ocean, from which situations they have been ele- 

 vated by the ordinary laws of volcanic agency. The mould forming ihe 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 hving 

 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 Hnk 

 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 indi- 

 cating the totality of the phenomena which have given rise to its adoption. 



As the human body, the bodies of the other animal?, 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 con- 

 sider living bodies in their acti^^e 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 flexibiUty of motion, the gentle warmth, the cheeks crim- 

 soned with the blushes of beauty, the briUiant 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 moulder- 

 ing 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 parti- 

 cles, 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 hving, 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 pre- 

 served 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 sub- 

 stance. All are formed with different parts, which we call organs, and fi-om which 

 they derive the appellation of organized beings. These organs united together form 

 a whole, which is a perfect unity in respect to form, dm-ation, and the phenomena it 

 exhibits ; and, as one of these properties cannot be abstracted from the rest vrithout 

 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, inde- 

 pendent 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 differ- 

 ent from those influencing the mixtm-es 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 similcLr beings, by the same actions by 

 which they were themselves produced. All exist for a time, variable for each indi- 

 vidual, 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 



