PREFACE 



THE preparation of this textbook was begun before the war at a 

 time when we wore both actively engaged in teaching at the London 

 Hospital Medical College, and when it was considered that we might 

 with advantage put together and harmonize the physiology we were 

 teaching. In order to secure uniformity of style, each section has 

 been written in the first instance by the same hand, and then finished 

 in its present form by careful collaboration between the two of us. 



While physiological research has been confined in many directions, 

 progress along certain lines has been especially remarkable since the 

 outbreak of war. We have endeavoured to take these recent ad- 

 vances into consideration, before completing the work, in spite of the 

 great difficulties under which we, in common with all physiologists, 

 have laboured. 



The book has been written with the primary object of giving to 

 the student in an easily understandable form the fundamental facts 

 and theories of physiology, bearing in mind the limitations necessary 

 in a student's textbook. We have followed the example of Michael 

 Foster, and have avoided burdening the students memory with the 

 names of authorities. When ready to leave the narrow scope of a 

 textbook for the wide realms of independent thought, those who 

 wish to extend their physiological knowledge can easily find their 

 way into the literature of research by means of the various archives and 

 journals of physiology. 



Although written primarily to meet the requirements of the 

 medical student, it is hoped that, in view of the ever -increasing 

 importance of the proper application of physiology to general medi- 

 cine, the work may also prove of value to the general practitioner. 



For the use of illustrations we are indebted to Dr. J. Barcroft, 

 F.R.S.; Professor W. M. Bayliss, F.R.S.; Professor W. B. Cannon; 



