VIEW OF NATURE. 
307 
you would find no difficulty 7 with regard to a nightingale and a 
rose, to discover to which of the kingdoms of nature they' belong ; 
yet, with respect to a polypus or coral, and a mushroom or a 
lichen, it would be somewhat difficult, without a previous knowl- 
edge of their classification, to say which is called animal, and 
which vegetable, or to give the distinctions between them. We 
have seen that the polypus may be increased by cutting shoots 
and engrafting them upon other animals, in the same manner as 
vegetables may be increased. 
With respect to sensation, some plants discover this, apparent- 
ly 7 even in a greater degree than some of the last orders of ani- 
mals ; the sensitive plant shrinks from the touch ; the Dionea 
suddenly closes its leaves upon the insect which touches them ; 
the leaves of plants follow the direction of light, in order to 
present their upper surfaces to its influence ; this you can ob- 
serve in flower pots placed by a window. The seed of a plant, 
in whatever situation it may be placed in the earth, always 
sends its root downwards, and its stem upwards ; in these cases, 
does there not seem as much appearance of sensation and in- 
stinct, and even more than ; n the lower orders of animals? 
We find then, that the possession, or want of instinct, does 
not constitute a mark of distinction between animals and plants. 
Some have attempted to draw a line of distinction, by 7 consider- 
ing, that locomotion, or the power of changing place, belongs to 
animals only ; but this seems to fail, since we find animals fixed 
to the bottom of the sea, or growing upon rocks, 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 an empyreumatic 
odour when animal substances are burning, similar to what we 
perceive in the combustion of bones ; but nitrogen has also been 
discovered in some vegetables. 
It appears then from a comparison between animals and veg- 
etables, that these beings are closely connected by the essential 
characters of organization ; that it seems impossible to distin- 
guish them by 7 any 7 trait that belongs exclusively to either; that 
the connexion between them appears the most striking in the 
least perfect species of both kingdoms ; and that as we recede 
from this point, the differences become more numerous and more 
marked. We may illustrate this view, by imagining two as- 
cending chains of beings, rising from one common point, each 
side of the chain becoming more and more unlike in proportion 
to the intervening distance from the centre. From this same 
central point, also proceeds the chain of inorganized substances ; 
Analogies between the lower orders of animals and plants — Chains of be- 
ings proceeding from one point. 
