264 Mr. Walter Heape. Ovulation and [ Mar. 6, 
their blood into the follicle itself, forming there a clot of blood, in the 
midst of which for many days the degenerating ovum may be seen. 
This result causes the brilliant suffused red colour of degenerate ripe: 
follicles at an early stage of the process; gradually the red colour is lost and 
results in a black patch which long persists, and which is reduced as time: 
goes on by the absorption of the contents of the follicle. 
The first rush of blood isolates the ovum and its discus proligerus, and 
subsequently washes away the rest of the epithelium from the walls of the: 
follicle, disintegrates the theca interna, and permeates the meshes of the theca. 
externa. The contents of such follicles are very brittle, and in sections are 
frequently lost, so that not infrequently this false corpus luteum appears. 
as a cavity bounded by the theca externa (cf. No. 23). | 
The absorption of the contents is carried out mainly by in-growing 
parenchyma cells, though a few leucocytes are also similarly engaged, and 
as the blood clot disappears its place is taken by the normal ovarian tissue.. 
Thus, the false and the true corpora lutea are markedly different structures. 
and are readily distinguishable in sections. 
Degeneration of Ova and Sterility —kIf the buck is withheld from a doe: 
during several consecutive periods of cestrus, most, if not all, the older and. 
many younger follicles then undergo degeneration. The loss of ova from 
this cause is so great that frequently during the remainder of that breeding 
season, and sometimes apparently for one or more future seasons, the animal 
is sterile. This prevention for a time of the normal functions of the 
ovary results in more or less persistent sterility, a point of interest to. 
students of the physiology of the generative system and not without economic. 
importance. 
Degeneration of Young Follicles: Variation and Nutrition—But. besides. 
degeneration brought about in this manner, there are other causes which 
induce degeneration of ova. In many ovaries in which there are healthy 
ripening ova in healthy follicles, degenerative changes are to be seen in 
others, in some of which it is the follicle, in others the ovum, which first. 
shows signs of disintegration. These are invariably younger follicles, and 
the cause of degeneration seems clearly to be associated with nutrition. 
In cases where follicles degenerate in the neighbourhood of other healthy 
follicles, want of nutrition is strongly indicated, and it 1s not improbable 
that competition is at work and is responsible for the loss. Degeneration 
of the ovwm, however, from the same cause, while it may be due to com- 
petition, may also be due either to want of vitality of the ovum or to want. 
of the requisite quality of nutriment, in other words to inability of these 
ova to assimilate what is obviously sufficient for the needs of neighbouring: 
