40 NATURAL BODIES. 



intimate composition must vary greatly; for, when burning, the animal 

 substance is readily known from the vegetable ; a fact, which, as Dr. 

 Fleming 1 has remarked, is interesting to the young naturalist, if un- 

 certain to which kingdom to refer any substance met with in his re- 

 searches. The smell of a burnt sponge, of coral, or other zoophytic 

 animal, is so peculiar, that it can scarcely be mistaken for that of a 

 vegetable body in combustion. According to Mulder, 2 there is this real 

 difference between plants and animals in composition, that cellulose 

 (C 24 H 21 21 ) forms the principal part of the cellular mass in plants ; 

 whilst in animals the primary material is gelatin (C 13 H 10 N 2 5 ) ; and to 

 this rule, he says, no exception has yet been discovered either among 

 animals or plants. 



2. Texture. In this respect, important differences are observable. 

 Both animals and vegetables consist of solid and fluid parts. In the 

 former, however, the fluids bear a large proportion : in the latter, the 

 solids. This is the cause, why decomposition occurs so much more 

 rapidly in the animal than in the vegetable ; and in the succulent more 

 than in the dry vegetable. If we analyze the structure of the vege- 

 table, we cannot succeed in detecting more than one elementary tissue, 

 which is vesicular or areolar, or arranged in vesicles or areolse, and 

 appears to form every organ of the body; whilst, in the animal, we 

 discover at least three of these anatomical elements, the areolar 

 analogous to that of the vegetable ; the muscular, and the nervous. 

 The vegetable again has no great splanchnic cavities containing the 

 chief organs of the body. It has a smaller number of organs, and 

 none that are destined for sensation or volition ; in other words, no 

 brain, no nerves, no muscular system ; and the organs of which it con- 

 sists are simple, and readily convertible into each other. 



But these differences in organization, striking as they may appear, 

 are not sufficient for rigid discrimination, as they are applicable only 

 to the upper classes of each kingdom. In many vegetables, the fluids 

 appear to preponderate over the solids ; numerous animals are devoid 

 of muscular and nervous tissues, and apparently of vessels and distinct 

 organs; whilst MM. Dutrochet, 3 Brachet, 4 and others, 5 admit the 

 existence of a rudimental nervous system even in vegetables. 



3. Sensation and voluntary motion. There is one manifest distinc- 

 tion between animals and vegetables. Whilst the latter receive their 

 nutrition from the objects around them irresistibly and without voli- 

 tion, or the participation of mind; and whilst the function of repro- 

 duction is effected without the union of the sexes, both volition and sen- 

 sation are necessary for the nutrition of the former, and for acts that 

 are requisite for the reproduction of the species. Hence, the necessity 



1 Philosophy of Zoology, i. 41. Edinburgh, 1822. 



Q The Chemistry of Animal and Vegetable Physiology; translated by Fromberg, p. 91. 

 Edinburgh and London, 1849. 



3 Recherches Anatomiques et Physiologiques sur la Structure Intime des Animaux, et des 

 Vegetaux, et sur leur Motilite. Paris, 1824. 



4 Recherches Experimental sur les Fonctions du Systeme Nerveux Ganglionnaire, &c. 

 2d edit. Paris et Lyons, 1837. 



6 Sir J. E. Smith, Introduction to Botany, 7th edit., by Sir W. J. Hooker, p. 40. Lond. 

 1833. 



