42 MAN, — THE ANIMAL 



probably happens. We must say, then, that the 

 ameba exercises choice and that it can interpret 

 stimuH. The technical term of coordination is 

 employed in this connection as indicating that the 

 ameba is able to use the information received from 

 the stimuli. 



The manner in which living protoplasm re- 

 sponds to external stimuli constitutes one of the 

 most essential distinctions between living and non- 

 living states. 



The consideration of these elementary responses 

 in protoplasm suggests the sense organs, nerves, 

 brain and muscles of man. It is true that in an 

 elementary way the ameba can carry on the same 

 kind of response as the man, although there is no 

 structural evidence of nerve, sense organ or 

 muscle. 



One is just as much at a loss to understand what 

 happens to the stimulus after it enters our brain 

 through the eye or ear. The many studies that 

 have been and are being made on the ameba and 

 other simple animals are all attempts to under- 

 stand what really is happening within the proto- 

 plasm. Every new fact about any form of life, 

 grasped by the human mind, helps it to explain 

 and understand all life. 



This microscopic bit of protoplasm in the body 

 of an ameba is clearly a fluid without any contain- 



