THE LEAF 131 



plicated than the most intricate stop watch and much 

 more going on in it. In our own bodies it is esti- 

 mated there are twenty-eight trillion cells, each one 

 having its own duty to perform, each one having a 

 nucleus and protoplasm, but unlike the leaf cells 

 without chlorophyll grains. Animal cells cannot 

 manufacture their own food to feed the animal. 

 They must depend on other animals or plant life. 

 We could not exist on this world of ours without 

 plant life. 



