PART I 



INTRODUCTION 



It is customary to divide the study of the human body 

 into three departments: (1) Anatomy, which is the science 

 that describes the structure of the body; (2) Physiology, 

 or the science of the functions, or uses, of. the various 

 parts of the body, and (3) Hygiene, or the science of 

 health, which treats of the care of the body and all its 

 parts for the purpose of maintaining the whole in its best 

 condition for usefulness and enjoyment. The term Physi- 

 ology, as applied to a schoolbook, however] "Js; o 

 to include all three of these lines of study., 



