36 VETEKIXAEV PATHOLOGY. 



different conditions. Loeb estimated that the average human 

 seminal ejaculation contained about y.Hi.OOO.OOO spermatozoa. 

 The average seminal ejaculation of a dog prol^ably contains 

 about the same number of spermatozoa as that of the human. 

 Lewis found that one stallion ejaculated (>.5 cc. of semen during 

 one service, each cmm. of which contained approximately l:!l,- 

 150 si)ermatozoa ; another stallion ejaculated !HI cc. of semen dur- 

 ing one service, each cmm. of ^\■]^ich contained approximately 

 S25,00(» spermatozoa. The quantity and the number of sperma- 

 tozoa per given volume of semen ejaculated during one service 

 of the bull has not been determined, at least the information has 

 not been found in the availalile literature. However, it is reasim- 

 able to suspect that the number of spermatozoa ejaculated dur- 

 ing a single service bj' the bull is equal to the number ejaculated 

 by a stallion during a single service. It is difficult to collect 

 the entire discharge of semen of a boar, but Lewis obtained 101) 

 cc. from a sint^le service of a l^nar and hv repeated examinations 

 he has determined that the semen from boars contains more 

 spermatozoa per given volume than that from stallions. There 

 would, therefore, be less chance for fertilization with an infected 

 spermatozoon in the horse, ox and hog than in man. Suppose 

 there were 1,000 tubercle bacilli infecting 1,000 spermatozoa that 

 were ejaculated by a Imll in one service, then there would be 

 one chance in about 12.000,000 of an infected spermatozoon 

 fertilizing an ovum, assuming that one seminal ejaculation of 

 the bull contains approximately the same number of spermatozoa 

 as one seminal ejaculation of a stallion. The chance is so slight 

 that it need not he considered. The oft'spring of animals affected 

 with some infectious diseases are more susceptible to those dis- 

 eases. For example, calves of tuberculous parentage are more 

 suscej)tible to tuberculosis than calves of non-tuberculosis 

 animals. 



Neoplasms or tumors are occasionally inherited or at least 

 there is an inherited predisposition to them. Dr. A. V. Meredith 

 of Lincoln, Kansas, submitted a tumorous growth for examina- 

 tion that was ol)tained from the left eye of a mule. The dam 

 of the nude, as well as four of her brothers and sisters had a 

 similar defect of the same eye. Cadiot refers to a family of dogs 

 in which there were carcinomata of the mammae for two successive 

 generations. 



I\Talformations, though usually of congenital origin, are 

 probably more frequently inherited than is any other type of 

 disea-^e. Thus a cryptorchid stallion was used' for breeding 

 purposes in a certain locality in Illinois and about 20^0 



