2 THE PHYSIOLOGY OF REPRODUCTION 



animals. As a general rule, I have confined myself to the physiology 

 of generation among the higher forms, and more particularly the 

 Mammalia, but I have not hesitated to discuss the reproductive 

 processes in the Invertebrata in cases where they seemed likely to 

 elucidate the more complex phenomena displayed by the higher 

 animals. The all-important questions of heredity and variation, 

 although intimately connected with the study of reproduction, are 

 not here touched upon, excepting for the merest reference, since 

 these subjects have been dealt with in various recent works, and any 

 attempt to include them would have involved the writing of a far 

 larger book. Similarly, the subject matter of cytology, as treated in 

 such works as Professor Wilson's volume on the cell or the recent 

 works by Professor Agar and the late Professor Doncaster, is also 

 for the most part excluded, t 



It may be objected that for a book on physiology much space 

 is devoted to the morphological side of the subject. This has 

 been done purposely, since it seemed impossible to deal adequately 

 with the physiological significance of the various sexual processes 

 without describing the anatomical changes which these processes 

 involve. 



In preparing this work I have been assisted by many friends. I 

 have been fortunate in securing the co-operation of Dr. William 

 Cramer and Dr. James Lochhead, of the University of Edinburgh. 

 Dr. Cramer has contributed the section on the biochemistry of the 

 sexual organs, while Dr. Lochhead has written the chapters on foetal 

 nutrition and the metabolism of pregnancy, a labour of no iuconsider- 

 able magnitude in view of the complexity of the subject. I take this 

 opportunity of recording my indebtedness to Mr. Walter Heape, 

 through whose influence I was first led to realise the importance of 

 generative physiology both in its purely scientific and in its practical 

 aspects. I am under no light obligation to Professor Sir Edward 

 Sharpey Schafer for valuable and ready help at all stages in the 

 preparation of this volume. Not only did he look through the original 

 manuscript of the chapter on " The Testicle and Ovary as Organs of 

 Internal Secretion," but he gave also much helpful advice and criticism 

 on various points connected with publication. Indeed, it is not too 

 much to say that had it not been for him, the book would scarcely 

 have been written. Sir Hugh K. Anderson, Master of Gonville and 

 Caius College, and Professor Sutherland Simpson have read the 

 manuscript or first proofs of the chapter dealing with*" The Accessory 

 Male Organs." The late Mr.'E. S. Carmichael, of the Royal Infirmary, 

 Edinburgh, read the section dealing with parturition. Professor J. H. 

 Ashworth looked through the chapter on " Fertilisation " in the first 

 edition ; and Professor F. G. Hopkins did the same for Dr. Cramer's 



