PLANTS AND ANIMALS DISTINGUISHED. 25 
analogy ends: the plant feeds on mineral matter, the ani- 
mal on organic. The former only has the power to con- 
vert the inorganic elements (carbon, oxygen, hydrogen, 
and nitrogen) into organic substance; the latter is de- 
pendent upon the organic substance thus prepared. But 
the Fungi also live on organic compounds (in a state of 
decomposition); and it is probable that some animals have 
the power of elaborating tissue directly from the mineral 
kingdom. The materials of nutrition are absorbed by all 
living bodies in a fluid state: the food of plants is gas- 
eous or liquid; that of animals is received in a form more 
or less solid, but afterward dissolved. While the absorb- 
ents of plants (roots and leaves) are external, those of ani- 
mals are distributed along the walls of a digestive cavity. 
Plants exhale less water, and animals more water, than 
they imbibe. 
In general, plants receive nourishment to grow, animals 
to repair waste. The fabric of the former, once completed, 
remains unchanged ; while the tissues of the latter require 
constant renewal. Plants are continually receiving ad- 
ditional members; animals are born perfect. In other 
words: in the nutrition of the former, addition is the 
prominent idea; in the latter, substitution. In the for- 
mer, the result is a straggling outline, with almost unlim- 
ited growth; in the latter, a finished, compact form.* 
Plants decompose, and animals recompose, carbonic 
acid; the one yielding the oxygen and fixing the carbon, 
the other exhaling carbonic acid and retaining some oxy- 
gen. Animals, therefore, inspire what plants set free: the 
food of the former undergoes oxidation ; that of the latter, 
deoxidation. This chemical antagonism, however, will not 
serve as a rigorous definition. Mushrooms and leafless 
parasites, all plants in the dark, germinating seeds and 
opening flowers, give off carbonic acid.’ Every plant be- 
gins life as an animal—a consumer, not producer: not till 
