PLANTS AND ANIMALS DISTINGUISHED. 
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pendent for their food on the compounds put together in 
plants. Colorless plants, as Fungi, possessing no chloro- 
phyl, feed, like animals, on organic compounds. No living 
being is able to combine the simple elements—carbon, ox¬ 
ygen, hydrogen, and nitrogen—into organic compounds. 
The food of plants is gaseous (carbon-dioxide and am¬ 
monia) or liquid (water containing substances in solution), 
that of animals usually more or less solid, though solid 
substances must be changed to liquids before being capable 
of absorption into the tissues. The plant, then, absorbs 
these foods through its outer surface, while the animal 
takes its nourishment in larger or smaller masses, and di¬ 
gests it in a special cavity. A few exceptions, however, 
occur on both sides. Certain moulds seem to swallow 
their food, 7 and certain animals, as the tape-worm, have no 
digestive tract. 
Plants are ordinarily fixed, their food is brought to 
them, and a large share of their work, the formation of 
organic compounds, is done by the energy of the sunlight; 
while animals are usually locomotive, must seek their food, 
and are unable to utilize the general forces of nature as 
the plant does. The plant is thus able to grow much more 
than the animal, as very little of the nourishment received 
is used to repair waste, while in most animals the time 
soon comes when waste and repair are approximately 
equal. But in both all work done is paid for by waste of 
substance already formed. 
In combining carbon-dioxide and water to form starch 
the plant sets oxygen free (6(CO 2 ) + 5(H 2 O) = C 6 H 10 O 5 + 
6(0 2 )): in oxidizing starch or other food the animal uses 
oxygen and sets carbon-dioxide free. The green plant in 
the sunlight, then, gives off oxygen and uses carbon-diox¬ 
ide, while plants, which have no chlorophyl, at all times, 
and all plants in the darkness, use oxygen and give off 
carbon-dioxide, like an animal. Every plant begins life 
