CHANGES IN THE OVARY 163 



less often, for it is improbable that they ovulate more frequently 

 than they come " on heat." Beard, however, denies that there 

 is any correspondence between " the heat or rut of Mammals " 

 and menstruation in the higher forms, saying that very httle is 

 required in disproof of the supposed relation. 



The theory that the whole prooestrous process, including both 

 the degeneration and the recuperation stages, is of the nature of 

 a preparation ^ on the part of the uterus for the reception of a 

 fertiUsed ovum is not opposed to any of the known facts. The 

 process is sometimes viewed as a kind of surgical " freshening " 

 of the uterus, whereby the ovum can be safely attached to the 

 mucosa during the heahng stage. It is possible, however, that 

 the changing of the uterine tissue is not the least important part 

 of the process. 



Emrys-Roberts ^ has made the further suggestion that the 

 secretion of the uterine glands, together with the blood and other 

 products of prooestrous destruction, may serve to provide a rich 

 pabulum on which to nourish the embryo during the earhest 

 days of pregnancy. 



In opposition to these theories it may be urged that pregnancy 

 has been known to take place in women who have never 

 menstruated, and that it may occur during periods of amenorrhoea, 

 or during the lactation period, when menstruation is sometimes 

 in abeyance. Such cases, however, are the exception, and it 

 must not be inferred that because the prooestrous function can 

 occasionally be dispensed with without inducing a condition 

 of sterihty, it normally plays no part in the physiology of 

 generation. 



It has been pointed out, however, that the severity of the 

 menstrual process in women is occasionally so great as to be 

 positively injurious, and that such cases evidently belong to the 

 category of constitutional disharmonies which Metchnikofi ^ 



' Kundrat and Engelmann, " Untersuohungen fiber die Uterusscbleim- 

 haut," Strieker's Med. Jahr., 1873. Lawson Tait, Diseases of Women, 1889. 

 For a farther discussion of some of the theories regarding the purpose of 

 menstruation see Heape, " The Menstruation of Semnopithecus entellus," Phil. 

 Trans. JB.; vol. clxxxv., 1894. 



" Emrys-Eoberts, "A Preliminary Note upon the Question of the Nutri- 

 tion of the Early Embryo," Pros. Soy. Soc. B., vol. Ixxvi., 1905. 



3 Metcbnikoff, The Nature of Man, London, 1903. 



