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PREFACE 



IN this book is embodied in large part the subject matter of a 

 series of lectures which it has been my privilege to deliver annually 

 to the students of the College of Physicians and Surgeons of Columbia 

 University. Fully realizing that the medical student is pressed for time 

 and is imbued with a definite desire to apply his physiological knowl- 

 edge in a practical way at the bedside, it has been my endeavor to 

 invade the field of Comparative Physiology no farther than is abso- 

 lutely necessary to form a thorough basis for the physiological problems 

 which are of special importance to medical men. For this reason, 

 I have usually allowed the different discussions to be preceded by brief 

 remarks of a more general character, hoping thereby to retain a happy 

 medium between Special Physiology and Comparative Physiology. 



The same principle I have followed with regard to Physics and 

 Chemistry. While the medical student of the present day has been 

 required to pass a certain number of courses in these subjects prelimi- 

 nary to the study of medicine, I realize that time stimulates forget- 

 fulness, and that he may not have been in a particularly favorable 

 position during his years at College to grasp the practical bearing of 

 many of the topics then dealt with. For this reason, I have thought it 

 advantageous to him, as well as to myself as a teacher, briefly to review 

 those physical and chemical principles which are more directly related 

 to the subject matter of Physiology. The same course I have followed 

 pertaining to Histology. 



Together with Anatomy, and often with an unmistakable attitude 

 of charity, Physiology has been regarded as one of the foundation 

 stones of modern medicine. It seems to me, however, that this mile- 

 stone has been passed some time ago, and that the sole hope of modern 

 medicine is Physiology, or in a larger sense, the experimental sciences. 

 Since it may, therefore, be contended that "Medicine is Physiology," 

 the student should make a conscientious effort to become thoroughly 

 acquainted with this subject. It is by no means an easy task that lies 

 before him, but having fulfilled this duty, the reward is large, because 

 no other science is quite so interesting as Physiology, and no other 

 combines theory and practice so happily. I venture to hope that this 

 book will help him in this attempt, in spite of its doubtlessly many short- 

 comings, for which I beg his generous indulgence. 



Inasmuch as the subject of Physiology is altogether too large to 

 be dealt with in detail within the space of an ordinary text-book, 

 brevity and the elimination of everything that may be considered of 



