PLANTS AND ANIMALS DISTINGUISHED 221 



ends: the green plant feeds on mineral matter, the 

 animal on organic. Some plants have the power to 

 form chlorophyl, the green coloring matter of leaves, 

 which uses the energy of the sunlight to form starch 

 out of the inorganic substances, carbon dioxide and 

 water. They are able also to form albuminoid matter 

 out of inorganic substances. A very few animals which 

 have a substance identical with or allied to chlorophyl 

 have the same power, but in general animals are de- 

 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, oxygen, hydrogen, and nitrogen into organic 

 compounds. 



The food of plants is gaseous (carbon dioxide and 

 ammonia) or liquid (water containing substances in so- 

 lution), 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 digests it in a special cavity. A few exceptions, 

 however, occur, since certain animals, as the tapeworm, 

 have no digestive tract but absorb liquid food through 

 the surface of the body. 



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 sun- 

 light; 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 re- 



