42 



normal, when the testis is showing degeneration, ver^" few spei*ma- 

 tozoa appear, in the later stages none. Many spermatids are pres- 

 ent in various stages, and some spermatocytes. Animals in the 

 hyper-thymic condition appear to be sterile." 



The foregoing references will, I hope, serve to bring out the facts 

 that environment and diet, together Avith the general body meta- 

 bolism and the endocrines, have a more or less profound effect 

 upon the development, growth, and functioning of the genital 

 system. In the experiments it has been shown that sterility is 

 not necessarily accompanied by any apparent microscopical 

 changes in the gonads, or even at times in the general body health. 

 Nor can w^e exclude impotency of the male entirely even when the 

 spermatozoa are normal in shape, and motility. Carnett, and 

 others (38), years ago stated: " Indeed, there is abundant clini- 

 cal proof to the effect that systemic conditions which have no ap- 

 preciable effect upon the motility or conformation of the sperma- 

 tozoa materially interfere with reproductive power." The entire 

 complex genital system is inseparably linked up with the body as a 

 whole, a fact which we must bear in mind at all times. 



Impediments to coitus may be due to great difference in the size 

 of the two mated individuals, psychic disturbances, or inability 

 to protrude the penis. Williams (17) mentions several physical 

 impediments, as deformity of the limbs or feet, sore feet, overload- 

 ing of the rumen, obesity, fear of falling, and paralysis. Coitus 

 may be somewhat delayed, or even not performed as the result of 

 a severe inflammation with sensitiveness of the penis or prepuce. 

 Occasionally tumors of the penis are encountered which may inter- 

 fere with prolusion of the penis, or its entrance into the vagina. 

 Not infrequently the penis is rendered incapable of protrusion as 

 the result of inflammatory adhesions, tuberculosis of the preputial 

 lymph glands, etc. 



Excessive sexual use, within certain limits, probably has not, in 

 itself, any material permanent effect upon the reproductive capac- 

 it}-. Tlie frequency with which bulls used to excess break down 

 sexually, is probably due to the devitalizing effect upon the tissues 

 of tlie genital organs, this opening the way to bacterial invasion 

 and other destructive influences. Over-use is probably not danger- 

 ous, unless continued over long ]ieriods. but at the same time it 

 offers greater opportunity for infection to be introduced into the 

 body from intercourse with large numbers of females. Lloyd- 

 Jones and Hays (47) carried on very interesting experiments on 

 the influence of excessive sexual activity of male rabbits on the 

 properties of the semen. Their plan was to mate male rabbits in 

 quick succession, and study the character of the semen on the 

 first service, and every fifth service thereafter. The safe limit 

 was twenty services in three hours. As would be expected, the 

 volume of the semen, after the first few services, became gradually 

 reduced in amount. " In rapidly successive services, the semen 

 becomes less viscous and tends to lose its charactertistic milky 



