PREFACE TO THE THIRD EDITION. 



THE present edition is in many respects a new book, for many parts 

 have been rewritten and the arrangement of the whole has been 

 altered. The book now consists of two parts, Part I., which deals 

 with Experimental Physiology, and Part II., which is devoted entirely 

 to Physiological Chemistry. 



The experiments upon muscle and nerve have been reduced in 

 number and the observations which can be made upon man have 

 been increased. 



The Authors wish to thank Drs. H. D. Haskins and J. H. Ryffel 

 for their able assistance in the revision of the chapters on Physiological 

 Chemistry and Dr. Kennaway for many criticisms and suggestions 

 upon the whole of the work. 



Dr. Hertz has contributed a special chapter upon the " Investigation 

 of the Motor Functions of the Alimentary Canal by means of the 

 X-Rays," and Dr. Ryffel one upon "Lactic Acid, its Estimation and 

 Significance." For this valuable assistance hearty thanks are given. 



Sept., 1910. 



