vi PKEFACE 



before beginning the study of this work. He will then be able to vary 

 the order of chapters in this book according to the part of physiology 

 which he is hearing about in his lectures or working at in his practical 

 classes. Those of my readers who are entirely unacquainted with 

 physiology might do well on a first perusal to omit Book I., dealing 

 with the general concepts of the science. 



I have deemed it a hopeless and indeed a useless task to give any 

 full account of the multifarious methods employed in the experimental 

 investigation of the different organs of the body. In most cases I 

 have consigned to small type a description of one or two typical 

 methods, which would suffice to show how the questions may be 

 approached from the experimental side. 



Throughout the work I have sought to show that the only founda- 

 tion for rational therapeutics is the proper understanding of the 

 working of the healthy body. Until we know more about the physio- 

 logy of nutrition, quacks will thrive and food faddists abound. Igno- 

 rance of physiology tends to make a medical man as credulous as his 

 patients and almost as easily beguiled by the specious puffings of the 

 advertising druggist. I trust, therefore, that the following pages 

 will be found of value not only to the candidate for a university 

 degree but also to the practitioner of medicine in equipping him for 

 his struggle against the factors of disease. 



In the selection of diagrams for the illustration of this book I 

 am especially indebted to Professor Schafer and to his publishers, 

 Messrs. Longmans, for the permission to make use of a large number 

 from Quain's "Anatomy" and from Schafer's " Essentials of His- 

 tology." I must also express my obligation to Professor Wilson for 

 the use of certain figures from his admirable work on the cell, to 

 the publishers of Cunningham's " Anatomy," and to many physio- 

 logical friends, especially to Dr. Mott and Dr. Gordon Holmes, for the 

 use of original diagrams. The index was kindly made for me by 

 Mr. Lovatt Evans. 



UNIVERSITY COLLEGE, LONDON 

 May 1912 



