CLASSIFICATION OF SCIENCES 111 



ogy the two questions have never been far apart. 

 They have evolved together, especially during 

 the last hundred years, prompting one another 

 to a more and more penetrating inquisitiveness. 

 The key-word of the one is structure, or organ- 

 ization; the key- word of the other is function, or 

 activity. The creature which our first ques- 

 tion killed and picked to pieces has to be put 

 together again and made to work! What does 

 it do? how does it do it? how does it go? how 

 does it keep agoing? how does it set other creatures 

 like itself agoing? how long can it go? how does 

 it cease from going? In other words, how does 

 the organism feel and move? how does it grow 

 and multiply? how does it waste, recover itself, 

 and finally, in most cases, die? Above all, what 

 is the secret of its activity and of its power of 

 effective response to the changeful order of 

 nature? " (Darwinism and Human Life, 1909, 

 p. 8.) The attempts to answer these and 

 similar questions have made the science of 



Physiology. 



Physiology is the science of the activity of 

 organisms. It is the study of the working of 

 living things. It considers plants and animals 

 and man in their dynamic relations, just as 

 morphology considers them statically. It takes 

 to do with habit and function, just as morphology 

 takes to do with form and structure. And the 



