24:0 COMPAEISON BETWEEN ANIMALS AND PLANTS. 



history, to say wbich is called animal and which vegetable. 

 "We have seen among the zoophytes, that the polypus, like a 

 vegetable, may be increased by cutting shoots and ingrafting 

 them upon other animals. With respect to sensation^ some 

 plants seem to possess this, apparently even in a greater degree 

 than some of the last orders of animals : — the sensitive-plant 

 shrinks from the touch ; the Dionea suddenly closes its leaves 

 upon the insect which touches them ; the leaves of plants fol- 

 low the direction of light in order to present their ujDper sur- 

 faces to its inHuence, as may be observed in flower-pots placed 

 in a window. The seed of a plant in whatever situation it 

 may be placed in the earth, always sends its root downward 

 and its stem upward ; in these cases, does there not seem as 

 much appearance of sensation and instinct, and even more, 

 than in the lower orders of animals ? 



383. We find, then, that the possession^ or want of instinct^ 

 does not constitute a mark of distinctio7i hetween animals and 

 plants. 



Some have attempted to draw a line of distinction, by con- 

 sidering that locomotion.^ or the poioer of changing place.)helo7igs 

 to animals onhj ; but this criterion seems to fail, since we find 

 animals fixed to the lottom of the sea, or growing upon roclcs^ 

 and plants moving upon the surface of the water. 



Another mark of distinction has been given, in the supposed 

 presence of nitrogen in animals.^ detected by a peculiar odor 

 when animal substances are burning, similar to what we per- 

 ceive in the combustion of bones ; but nitrogen having teen 

 discovered in some vegetables.^ this proof is no longer considered 

 infallible. 



384. It appears, then, from a comparison between animals 

 and vegetables, that these beings are closely connected by the es- 

 sential characters of organization ; that it is impossible to dis- 

 tinguish them by any trait that belongs exclusively to either ; 

 that the connection between them appeon^s the most striking in the 

 least jyerfect species of both kingdoms / and that, as we recede 

 from this point, the difterences become more numerous and 

 more marked. We may illustrate this view by imagining two 

 ascending chains rising from one common point, each side of 

 the chain becoming more and more unlike in proportion to the 

 interveniwg distance from the center. From this same.^ central 

 point also proceeds the chain of inorganized substances ; — soone 

 imperfect animals resembling plants in their outward form ^ 

 some., both of animals and plards, resembling minerals in their 

 Jia/rd and calcareous coverings and shapeless forms. 



383. Distinction between animals and plants.— 384. Resemblances. 



