DIFFERENCES BETWEEN PLANTS AND ANIMALS. yr 
not only is it now well known that no line can be drawn 
dividing the two kingdoms, but there is reason to be- 
lieve that some organisms which at one period of their 
lives most resemble animals, are at another time as distinctly 
vegetable. It has been proposed that all these doubtful 
organisms should be united together to form a new kingdom, 
neither animal nor vegetable, to be called the Protista, but 
this proposal has not been favourably received. 
The following are the chief points of difference, none 
of which, however, will hold good in all cases :— 
js 
2. 
With the exception of some parasites, animals generally 
possess a mouth and stomach. 
Animals contain a larger amount of nitrogenous com- 
pounds than plants. 
. Animals do not liberate oxygen when exposed to sun- 
hight. 
. Plants produce protein, animals consume it. 
. Vegetable cells secrete a wall of cellulose, while animal 
cells remain more or less naked. 
. Voluntary motion is chiefly confined to animals. 
. Sensation, as usually understood, is confined to the 
higher animals. 
