1 1 6 Diseases of the Genital Organs 



the ovum has passed down the horn corresponding to the 

 ovary from which it emanated, thence across the uterine 

 body cavity and up the opposite horn. My observation 

 makes it perfectly clear that the alternating of the fetus and 

 the corpus luteum is not proof of migration. 



The abnormality of estrum (and coitus) appears to have 

 no serious peril for either the pregnant animal or the fetus. 

 It is clear evidence of a pathologic state, but many cows and 

 heifers show frequent estrum and copulate freely without 

 showing any marked tendency to abort or for the pregnancy 

 to terminate unfavorably in any marked respect. Some of 

 them abort, it is true, but I have been unable to learn that 

 their tendency to' abort is greater than in pregnant cows 

 which do not shdw estrum. A few cases have occurred under 

 conditions which have led some to believe that coitus caused 

 abortion almost immediately. Thus I recall one cow which 

 came in estrum in the sixth month of pregnancy, copulated, 

 and the next day aborted. In other instances, a cow carry- 

 ing a desiccated fetus develops estrum, copulates, and a 

 few hours later expels the mummy. I think it reasonably 

 certain that the facts have been misinterpreted, and that, 

 instead of the coitus causing the expulsion of the fetus, the 

 corpus luteum has atrophied, an ovisac has ripened, estrum 

 and coitus have occurred, and because of the atrophy of the 

 corpus luteum, not because of coitus, the uterus contracts 

 and expels the fetus. That is, instead of the estrum and 

 copulation causing the abortion, the disease has brought 

 about the changes in the ovary, the estrum, the copulation, 

 and the expulsion of the fetus. The problem merits further 

 study. 



Menstruation following estrum in pregnancy is incom- 

 patible with the life of the fetus, because the menstrual 

 blood consists of a hemorrhage emanating from the pla- 

 cental areas (cotyledons) of the uterus. Menstruation 

 would, therefore, result iirst of all in a hemorrhage between 

 the maternal and fetal structures which would force the two 

 structures asunder (compare "Desiccation of the Fetus"). 



