CAUSE OF EVOLUTION 377 



life as a single cell and swims around in the ocean for 

 months until it finds a mate, then they settle down and 

 commence housekeeping on a suitable rocky place on the 

 bottom of the sea, and there they begin to multiply in 

 numbers and build an enormous colony which we call the 

 sponge. The building process, however, is quite slow, as 

 they gather the food and building material from the sea 

 water. 



The sponge building cells live on smaller cells usually 

 called bacteria and microbes. These smaller cells are by 

 no means less intelligent in their place in life than the 

 larger ones. The cells that know how to make their own 

 food like starch, sugar and other carbohydrates are gen- 

 erally smaller than the other cells. They usually make 

 only stationary abodes like plants and trees. It seems, 

 however, that upon their knowledge of how to make food 

 and several other kinds of material depends the existence 

 of all the others. The following from a daily paper seems 

 to be a true expression of the situation : "Few things in 

 science are more startling than the realization that man's 

 existence depends absolutely on tiny vegetables so small 

 that they can only be seen with the most powerful micro- 

 scope. It is these minute growths which produce the 

 larger vegetables man uses for food and were it not for 

 them the human race would starve to death. 



"The origin of life may be a disputed matter, but the 

 operation of life is unquestionably due to microscopic 

 forms of plant life which we call bacteria. There have 

 been many learned definitions of the differences between 

 plant and animal, but few are more satisfactory than that 

 which declares a plant to be an organism that can derive 

 its food from mineral substances and an animal to be an 

 organism that cannot." 



Did you ever realize that the cells of every plant or 



