Parovarian Cysts 425 



11. Corpora Nigra 



I have seen two instances of black instead of yellow bodies in the 

 ovaries of pregnant cows. One was of normal size, form, and con- 

 sistency; the other was greatly enlarged, as shown in Fig. 137. The 

 bodies were a dark blue-black. Aside from the excessive size of one 

 and the color of both, they appeared perfectly healthy. No signs of 

 disease were observed in any part of the genital system or else- 

 where. Neither the cause nor the significance of the condition was 

 apparent. It is probably a mere "sport" without relation to sexual 

 health or efficiency. 



Fig. 137 — Corpora Lutea of Pregnancy. For comparison with 



Cystic Corpora Lutea. 



/, 'Adherent ovary ; 2, corpus nigrum of pregnancy ; j, corpus luteum of 



pregnancy ; 7, mate to j ; 5, 6, corpora lutea of pregnancy ; 8, 



enlarged corpus nigrum ; g, 10, twin corpora lutea ; 



12, fresh corpus luteum. 



12. Parovarian Cysts 



Cysts occur now and then in close proximity to the ovaries, ap- 

 parently due to cystic changes in remnants of the Wolffian bodies 

 or of the Wolffian ducts. In the mare, as illustrated in Fig. 70, 

 Chapter XI, these cysts may become a menace to the health or to 

 the life of the animal. This I have not observed in the cow al- 

 though it may evidently occur. Instead I have observed usually 

 small coiled tubular cysts without known significance for the ani- 

 mal. Their chief interest lies in their close proximity to the ovi- 

 ducts and their confusing likeness to hydrosalpinx, which may lead 

 the veterinarian to pronounce a perfectly fertile animal incurably 



