PREFACE. 13 



book will be found useful to many practitioners of medicine who may wish to 

 keep themselves in touch with the development of modern physiology. For this 

 class of readers references to literature are not only valuable, but frequently 

 essential, since the limits of a text-book forbid an exhaustive discussion of 

 many points of interest concerning which fuller information may be desired. 



The numerous additions which are constantly being made to the literature 

 of physiology and the closely related sciences make it a matter of difficulty to 

 escape errors of statement in any elementary treatment of the subject. It can- 

 not be hoped that this book will be found entirely free from defects of this 

 character, but an earnest effort has been made to render it a reliable repository 

 of the important facts and principles of physiology, and, moreover, to embody 

 in it, so far as possible, the recent discoveries and tendencies which have so 

 characterized the history of this science within the last few years. 



