38 



sxinrtrested, to any toxic influence on the organs of generation, but 

 to the same causes as tho.se which restrict breeding in a state of 

 nature to certain particular seasons, and that the sexual instinct 

 can only be called into play in response to certain stimuli, — the 

 existence of which depends to a large extent upon appropriate 

 seasonal and climatic changes." 



Diet: Under tliis heading we may include not only the effect 

 of deficient food, but also constitutional disorders, as a result of 

 "which the oi'gans of generation and those glands guarding their 

 function I'cceive insufticient nourishment. It is a well known fact, 

 and long has l>cen. that animals fail to breed when they are in a 

 run down condition or when they are fed a deficient diet. Gary 

 (35), quoting Hagner, states that the virility of the spermatozoa 

 is often in direct proportion to the general physical condition of 

 the patient. 



Reynolds (di) emphasizes the fact that it is an established 

 l^rinciple among animal breeders that a high protein diet in both 

 sexes is essential to full fertility. " Oligospermia with defieient 

 vitality of the spermatozoa is not infrequently found from con- 

 stitutional disorders. It can easily be demonstrated in animals 

 that both low diet and conditions of life that produce a nervous 

 excitable state are attended by oligospermia." Animals that are 

 closely confined, those that are over-fat (show animals), as well 

 as those fed a deficient ration very frequently fail to breed,' but 

 exercise and change of diet soon overcome the impotency. 



Dutscher, Hart, Steenbock. and other biological chemists have 

 done extensive work to show the essential importance of vitamines 

 and minerals in the diet. Their results indicate that animals can- 

 not thrive and breed normally when fed a diet composed solely of 

 the products of one plant. There must be variety, and there must 

 be not only a correct nutritive ratio, but the mineral and vitamine 

 content must be present as well. Cows fed on the products of one 

 plant often failed to ])reed, and if conception occurred, it in- 

 variably^ resulted in a premature birth, or the birth of weak and 

 poorly nourished calves. The work of these authors is funda- 

 mental, and Ijrings out many important points. Is it not probable 

 that the deficient diet results in Aveakened tissues which are easier 

 proy to the invasion of bacteria? 



Macomber and Reynolds (39) experimented upon white rats 

 to determine the effect of defective diet as a cause of .sterility. 

 They call attention to the confusion caused by the application of 

 the term sterility to most, or all, infertile matings. They believe 

 that failure of reproduction is, in fact, the result of cleereased 

 fertility rather than of actual sterility on the part of the two indi- 

 viduals concerned. " There are certainly a large number of in- 

 fertile matings which are purely functional and due to physiologic 

 alterations or local conditions. Such physiological alterations more- 

 over coexist in the sterilities of ])atholoo:ic origin and when un- 

 recognized and consequently unremedied, undoubtedly explain a 



