274 Diseases of the Genital Organs 



tozoa. These occur mainly as abnormal development or ar- 

 rest in development. Quite frequently I have seen extremely 

 large spermatozoan heads (megalocephalia) which so far as 

 determined are otherwise normal. Abnormally small heads 

 appear with much greater frequency. Morphological altera- 

 tion in any considerable proportion of the spermatozoa defi- 

 nitely decreases the procreative capacity of the bull. The 

 germinal cell may also be of low vitality without showing 

 morphological deviations. It is a well demonstrated fact 

 that the vitality of some bulls is so lowered that a healthy 

 vigorous calf is rarely produced. The cause for this may 

 be an inherent weakness, the devitalizing effect of a general 

 constitutional disturbance, or a local inflammation of the 

 germinal epithelium. 



My studies of numerous herd sires bring out many in- 

 teresting problems. Since it has become my regular prac- 

 tice to examine the semen of bulls in herds where there is 

 a high rate of abortion, I have been interested to find that 

 the spermatozoa almost always show marked pathologic 

 changes. I have not as yet been able to correlate such 

 changes with any specific infection. From results thus far 

 obtained, it appears unsafe to conclude that abortions oc- 

 curring in a herd are due to a specific disease of the female, 

 chiefly or alone, if the sire is not first subjected to a thor- 

 ough examination. 



Although it has been impossible to work out all data on 

 bulls examined up to the present time, the results so far in- 

 dicate : 



(1) that sterility of varying degrees in bulls is very com- 

 mon, 



(2) that such sterility is associated commonly either with, 

 an arrest in the development of the sperm cell or with dis- 

 integration after reaching maturity, 



(3) that, as the sterility is accompanied, in a large pro- 

 portion of the cases so far studied, by spermato-cystitis, 

 with no atrophic orchitis, it appears that the destruction or 

 devitalization of the spermatozoa is due to the toxic sub- 

 stances derived from bacterial infection. 



