PREFACE. 



THIS book was written primarily for medical and dental practitioners 

 and students. It emphasizes, however, the mechanism of sense-organs, 

 nerves, and muscles as the basis of the individual's efficiency; and it is 

 the first text-book of medical physiology to recognize the more and more 

 insistent demands of the mental process. For both of these reasons 

 it is also especially adapted to the needs of students and teachers of 

 physical education and of psychology. 



The great indebtedness of the author to some of his colleagues and 

 students in the preparation of the text and the illustrations is hereby 



gratefully acknowledged. 



G. V. N. D. 



