PREFACE 



In preparing this little book I have been actuated by the desire 

 to supply those who are interested with a concise account of the 

 more important sexual and reproductive processes in the higher 

 animals and man. Although it is called " An Introduction," the 

 subject is dealt with much more fully than is done in any ordinary 

 text-book treating of the whole of physiology. Headers who 

 require a more extensive knowledge may be referred to my 

 larger work on " The Physiology of Keproduction," and to 

 Professor Lipschiitz's book on " The Internal Secretions of the 

 Sex Glands." The present work is intended primarily for 

 biological, medical, and agricultural students, but it is hoped that 

 it may be of use also to others who possess only a rudimentary 

 knowledge of zoology or physiology. Indeed, had I not received 

 repeated requests to write such a book as this aims at being, I 

 should hardly have made the attempt. 



My thanks are due to Dr A. S. Parkes who has very kindly read 

 the section on the Determination of Sex, and given me the benefit 

 of his helpful criticism. I am likewise indebted to Mr J. T. 

 Saunders who has looked through the chapter on Pregnancy. 

 I wish to thank Mr J. H. Bullock for the care he has taken in the 

 preparation of the index and in the final revision of the proofs. 

 I am under obligations also to all those authors and pubHshers 

 who have kindly allowed me to reproduce illustrations from the 

 respective works belonging to them. 



The subject of the book is one which is rapidly advancing, 

 and I have taken the opportunity of including in it some account 

 of investigations which have been published since the last edition 

 of my larger work was issued. The present work may therefore 

 be regarded as to some extent also a supplement to my former 



