10 WHAT THE STUDY OF PHYSIOLOGY MEAJfTS 



Physiology. — Anatomy tells us only of the structure 

 of the lifeless body. It is physiology that tells us of the 

 action of the parts in the living body. Here the problem 

 of investigation becomes difficult, but again we call to aid 

 the fact that vital processes in plants and animals are 

 similar to those in our own bodies, and the experiments 

 we employ with the former tell us the workings of our 

 own body. These experiments are supplemented by the 

 reports of surgeons of their operations on human bodies, 

 while another branch of science, called 'physiological chem- 

 istry, has taught us how to reproduce artificially many of 

 the actions which take place normally in our bodies. 



Hygiene. — The best engineer is the man who knows 

 not only how his engine is made and acts, but also how 

 to keep it in order and to run it to the best advantage. 

 It is this knowledge — how to run our bodies to the best 

 advantage, that is, to keep them healthy — that the study 

 of hygiene gives us. It can be acquired only by taking to 

 ourselves the experience of those most familiar with the 

 running of our bodies. There are, however, certain of 

 these experiences which have been formulated under the 

 laws of sanitation which will give us a better foundation 

 for our apprenticeship. Such laws are those that have 

 been formulated by doctors, physicists, and bacteriologists, 

 and we shall study them in their proper place. 



Relation to other sciences. — The preceding pages indi- 

 cate in a general way what the scope of our study is to be. 

 What relation does this study bear to other sciences? 



Biology (pios, life; logos, speech) is the name given to 

 the study of living as distinct from lifeless matter. This 

 subject naturally groups itself into the study of plants, 

 botany, and the study of animals, zoology. From what has 



