Infections of the Ovum, Embryo and Fetus 491 



semen during coitus. If the cows served by such a bull be- 

 come pregnant, they largely abort. It is quite unnecessary 

 to invoke mysterious infections to account for any and all 

 abortions. The infections are present, abundant, and potent. 



(b) Abortion is world-wide and is seen in all mammalia. 

 According to the highest authorities upon human obstet- 

 rics, 25 per cent, of pregnant women abort. Statistically 

 the rate of abortion is far less among domestic animals, but 

 that may be statistically only. I have previously stated that 

 the term abortion, as commonly used, signifies the observed 

 expulsion of the fetal cadaver. Abortion statistics are neces- 

 sarily based upon the observed phenomenon. Hence the 

 more accurate the observation, the higher statistically is the 

 rate of abortion. Such being the case, if the expulsion of 

 the embryonic or fetal cadaver were of equal frequency in 

 all mammalia, statistically woman would occupy first place, 

 the dairy cow next, followed by beef cows and other domes- 

 tic females in order of the accuracy of observation of those 

 who are in immediate charge. Available statistics from 

 dairy herds indicate that approximately 10 to 15 per cent, 

 of pregnant cows and heifers are observed to abort. How 

 many fetal cadavers are expelled unseen is pure guesswork, 

 but, if the opportunity for observation were as good as in 

 the human family, the probabilities are that the abortion 

 rate in cows would statistically equal or exceed that recorded 

 for woman. 



The phenomenon of abortion is probably more frequent in 

 dairy than in beef cattle. Certainly it is more frequently 

 seen, because the dairy cow is under very much closer ob- 

 servation than any other domestic animal, except possibly 

 pet cats and dogs. 



If the question is approached from a different angle, and 

 the reproductive efficiency of animals studied, there is far 

 greater accord between the various species and strains. If, 

 for example, the reproductive efficiency of pedigreed dairy 

 and beef cows be compared, it will be found that there is no 

 notable difference. In many pedigreed beef herds, especially 

 show herds, the reproductive ratio drops to 50 per cent, of 



