164 THE PHYSIOLOGY OF REPRODUCTION 



has shown to be so common in the organs and functions of the 

 generative system. 



Geddes and Thomson 1 also have called attention to the 

 pathological character of menstruation, as evidenced not only 

 by the pain which frequently accompanies the process, and the 

 local and constitutional disorders by which it is often attended, 

 but by the general systemic disturbance which always occurs 

 synchronously with it. These authors interpret the discharge 

 as a means of disposing of the anabolic surplus which is con- 

 sumed during pregnancy by the developing embryo. A similar 

 view is adopted by Webster, 2 who associates the introduction 

 of menstruation (as distinguished from the prooestrum of the 

 lower animals) with a diminished fertility. 



Reference has already been made to the " Wellenbewegung " 

 or " wave " hypothesis regarding the nature of menstruation 

 (see p. 67). 



The physiological cause of the prooestrum, and the probable 

 part played by the ovaries in this connection, will be discussed 

 at some length in a later chapter. 



1 Geddes and Thomson, The Evolution of Sex, Revised Edition, London, 

 1901. 



2 Webster, " The Biological Basis of Menstruation," Montreal Med. Jour., 

 April 1897. 



