CRYPTOGAMS 269 



operating in harmony to do a special work. This work is 

 the function of an organ. 



The root is an organ whose function is to absorb plant 

 foods, to anchor the plant to the soil, and to store food. 

 The stem is an organ whose function is to carry sap up and 

 down from root to leaf and back, to bring the leaves into the 

 light, and to store food. The leaf is an organ having many 

 important functions. 



The entire plant or animal body, being composed of or- 

 gans, is known as an organism; and hence the substances 

 which come from plants and animals are distinguished as 

 organic substances. 



