PREFACE. 



IN making this little book, I have tried to give to the 

 student a definite impression, in outline, of the structure 

 and functions of the human body. To this end I have 

 tried to omit all statements that would confuse the picture 

 by overloading it, and all statements that could not be 

 understood by those who will be its most numerous read- 

 ers. I have not told them, for example, that the re-action 

 of the saliva is alkaline, and that of the gastric juice acid, 

 because for many of them that statement would have no 

 meaning. I have not mentioned the names of many of 

 the muscles, because it is difficult and unnecessary to 

 remember them. 



The laws of hygiene are given in connection with the 

 facts of anatomy and physiology from which they are 

 derived. Learned in this way, they will remain in the 

 mind as guiding principles, and not simply as the dicta 

 of authority. 



In treating of the effects of stimulants and narcotics, I 

 have endeavored to set forth facts which are susceptible 

 of abundant proof, and which are of the most importance, 

 practically, to those for whom this work is designed. 



WILLIAM THAYER SMITH. 

 HANOVER, N.H., August, 



