144 INTRODUCTION TO SEXUAL PHYSIOLOGY 



in cases of abnormal vaginal secretion, where the spermatozoa 

 are apt to be killed before they can effect an entrance into the 

 uterus, and in other cases where there is an inability on the 

 part of the vagina to retain the semen after coitus. 



Artificial insemination has been practised on mares with 

 highly successful results, many ^^aluable animals having been in 

 this Avay saved for breeding, when otherwise they would have 

 been sterile. Moreover, several individuals may be successfully 

 impregnated as a result of one service by a male. 



Other Causes of Sterility 



Sterility may be due to diseases of manifold kinds, both those 

 affecting the organism as a whole, and those relating to the 

 generative organs (such as the venereal diseases), but the con- 

 sideration of these belongs to the science of pathology and is 

 outside of the subject of this book. Failure to produce off- 

 spring may also be due to sexual aberrations, resulting in 

 impotence or absence of normal desire. Such conditions are not 

 necessarily harmful in themselves and may be consistent with 

 normal health and well being. Some of them are to be regarded 

 as psychological manifestations of a congenital intersexual 

 state comparable to those intermediate sexual conditions which 

 occur in many animals. They probably have a hormonic basis. 



Sexual aberra-tions are usually deviations from the normal 

 ])rocesses, and most of them have been observed in some degree 

 in the lower mammals under conditions where it is impossible 

 to gratify the usual im})ulse. This is the case with masturbation, 

 the evil consequences of which were formerly much exaggerated. 

 There can be no doubt, however, that masturbation, when carried 

 on to excess, is exceedingly harmful and may lead to impotence, 

 but it is also true that over-indulgence of the normal sexual 

 impulse is deleterious. With animals in a state of nature, the 

 possibility of sexual excess is guarded against by the prolonged 

 periods of quiescence, but as is well known to stock breeders, 

 too frequent sexual intercourse or indulgence at too early an 

 age has a deteriorating effect upon the male kept for the purpose 

 of the stud. 



