2 THE PHYSIOLOGY OF REPRODUCTION 



the male and female reproductive organs, by Professor Nagel 

 and Dr. Sellheim, in Professor Nagel's " Handbuch der Physi- 

 ologic des Menchen," " Experimental Zoology," by Professor 

 T. H. Morgan, and the writings of Mr. Walter Heape. 



The present volume is addressed primarily to the trained 

 biologist, but it is hoped that it may be of interest also to 

 medical men engaged in gynaecological practice, as well as to 

 veterinarians and breeders of 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 re- 

 production, 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 sub- 

 ject matter of cytology, as treated in such works as Professor 

 Wilson's volume on the cell, is also for the most part excluded. 



It may be objected that, for a book on physiology, too 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 L'ochhead, 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 fo?tal nutrition and the 

 metabolism of pregnancy, a labour of no inconsiderable magni- 

 tude 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 



