176 



ANIMAL. 



limbs, constitute the character of this class. The or- 

 ganisation of (he \Ttcl)nil animals presents a strik- 

 ing analogy throughout. I. Mammalia ; producing 

 their young alive, which they suckle liy teats ; having 

 warm blood ; a heart with two \entricles ; lungs; a 

 convoluted brain, with a corpus callosum ; five sen- 

 ses; a muscular diaphragm between the chest and 

 the alxlominal ivity ; seven cervical vertebra (one 

 species excep'.ed, which has nine). The mammalia, 

 among which man is included, are generally the most 

 intelligent of animals : they are divided into orders, 

 according to the structure of their teeth and their 

 leet, which organs determine the habits and manner 

 ot life in animals. H. Birds, aves ; oviparous; the 

 1 1;:;^ covered with a calcareous shell ; without milk 

 or teals ; heart and blood like those of the mam- 

 malia ; lungs ; no diaphragm ; no teeth apparent on 

 the jaws, which are called the beak ; feathers and 

 wings ; projecting sternum, which completes the ap- 

 paratus for flying ; a gizzard for a stomach ; no ex- 

 ternal ear. These animals are the only ones which 

 sleep standing ; they are divided into orders, accord- 

 ing to the structure of the beak and feet III. 



Reptiles ; oviparous ; the eggs without shells, and 

 sometimes fecundated without coition ; single heart; 

 blood almost cold, and red. The reptiles indisputa- 

 bly form a separate class, but they have few common 

 characters peculiar to them ; some are inclosed in 

 a bony shell ; others are naked ; and others are 

 covered with plates, scales, or rings. There are 

 some which have limbs; others, without the least 

 trace of them ; and others, in which the number and 

 structure of the limbs vary. Some undergo trans- 

 formations like insects, and are, at one period of 

 their life, real fish, and for the rest of their days, little 

 quadrupeds. IV. Pisces, fish; oviparous; eggs 

 without shell or albuminous envelope, and fecundat- 

 ed without coition; single heart; blood cold and 

 red ; no real limbs, their place being supplied by 

 vertical fins : this vertical disposition of the fins is 

 sufficient to distinguish, at the first glance, fishes 

 from the cetaceous animals, which have horizontal 

 fins ; the body is naked, when not covered with 

 scales ; the skeleton is destitute of solidity, and, in 

 the lower species, is reduced to a mere cartilaginous 

 vertebral column. **. Mollusca; no skeleton; the 

 muscles attached to a soft skin, which is sometimes 

 naked, and sometimes covered with shells of very 

 various forms. The nervous system, in these ani- 

 mals, is confounded with the other parts ; none of 

 the organs is protected by a bony case ; the nervous 

 system is composed of several ganglia, a sort of little 

 brain, connected by sensitive filaments. The organs 

 of nutrition and generation are very complicated in 

 some ; they appear to have but two senses, touch 

 and taste, but some have also sight ; they breathe by 

 gills, and liave sometimes three hearts. Cuvier 

 divides the molluscce into six orders : the cephalopo- 

 da, pteropoda, gasteropoda, acephala, branchiopoda, 

 and cirrhopoda. ***. Articulated. Their nervous 

 -ystem is composed of two long cords, running the 

 whole length of the body, interrupted, at intervals, 

 by knots, or ganglia, the first of which is always the 

 largest ; the blood is cold, generally a white lymph, 

 except in the first order, the annelides, in which it is 

 red. The body and limbs, when they have any, are 

 composed of rings. This great division will proba- 

 bly undergo some modifications hereafter. I. Annd- 

 itits ; heart fleshy, visible; blood red; breathe by 

 gills, the position of which is various ; body compos- 

 ed of articulated rings ; no feet, sometimes thread- 

 like members in their stead. The annelides are 

 hermaphrodites, and probably oviparous. II. Crus- 

 taceous ; heart composed of one fleshy ventricle ; 

 blood white, circulates ; breathe by gills ; provided 



1 with antenna', commonly with four, and several 

 transverse jaws ; they are oviparous, and the sexes 

 are distinct. 111. *-lrnr/,niiles, spiders; head and 

 thorax united; no antenna-, nor gills ; breathing by 

 trachea-, or by pulmonary bags ; distinct sexes ; - 

 the young undergo no complete transformation ai'ier 

 they are hatched, number of eyes and feet variable.. 

 IV. Insects; no heart; lymph instead of blood; 

 breathe by trachea?; body divided into three impor- 

 tant parts, the head, which supports the antcnn.v, 

 and compound eyes, consisting of numerous facets ; 

 the thorax, to which are attached the feet, to the 

 number of six, and the wings, to the number of four 

 or two; finally, the abdomen, containing the princi- 

 pal viscera: sexes distinct ; oviparous; generate by 

 copulation; the young undergo wonderful transfor- 

 mations. Insects propagate but once during their 

 life. They are divided into orders, according to the 

 structure of the mouth, of the tarsus or foot, of the 

 antennae, and of the wings. ****. Radiated. This 

 class is distinguished from the three preceding almost 

 entirely by negative characters, the animals includ- 

 ed in it liaving few characters in common. Abor- 

 tions of nature, provided only with the incipient 

 forms of organisation, they show no traces of circula- 

 tion, no organs of sense, no distinct nervous system : 

 the organs of respiration are indistinct; those of 

 digestion sometimes complicated, sometimes consist- 

 ing only of a sack without an outlet ; sometimes ex- 

 hibiting organs, of which the action is visible, but 

 the functions unknown ; some of them manifest u 

 tendency to the radiated formation, and many are 

 composed of rays, that is, of tentacula diverging re- 

 gularly from the centre to the circumference ; but 

 this character is far from being universal, since many 

 of this class are perfectly spherical or membranous, 

 without the least tendency to the radiated structure. 

 They all inhabit the water. I. Echinodermata ; dis- 

 tinct organs of respiration and circulation ; the viscera. 

 contained in an interior cavity formed by the spines 

 disposed in rays, and sometimes star-formed ; they in- 

 habit the sea. II. Intestlni, intestinal worms ; long 

 body, without Ifrubs ; no distinct viscera , except a long 

 digestive canal ; parasites of other animals, in whose 

 bodies they are found ; it is not known how they enter 

 them, nor is any thing known of their manner of re- 

 spiration and generation. III. Acalephee, sea-net- 

 tles; body orb cularorradiated,containingadigesti\e 

 sack ; no organs of circulation, respiration, or genera- 

 tion distinguishable ; some of them, however, emit 

 a substance, which might be taken for eggs, and 

 which, when touched, excites a tingling sensation in 

 the skin, similar to that produced by nettles ; the 

 mouth serves as an anus ; they inhabit the sea. 

 IV. Polypi; body soft, contractible, forming an in- 

 testinal sack, which presents the appearance of an 

 orifice surrounded by tentacula ; no appearance of 

 organization which would lead us to suppose them 

 endowed with any sense except that of touch; they 

 are found only in the water, but inhabit both salt 

 and fresh. V. Infusoria; bodies transparent, con- 

 tractible, microscopic ; no organ discernible. For 

 the mental powers of animals, see the article I'n fin-- 

 standing. 



ANIMAL HEAT is that property of all animals, by 

 means of which they preserve a certain temperature, 

 which is quite independent of that of the medium by 

 which they are surrounded, and appears rather to h.- 

 in proportion to the degree of sensibility and irrita- 

 bility possessed by them. It is greatest in birds. 

 The more free and independent the animal is, tin- 

 more uniform is its temperature. On this account, 

 the human species preserves a temperature nearly 

 equal, about 96100 Fahr., in the frozen regions 

 at the pole, and beneath the equator; and on this 



