148 GEORGE W. CORNER 



by a few strands of cytoplasm. This rearrangement of the discus 

 proligerus was long ago shown by Bischoff ('78) to be a trust- 

 worthy sign of impending rupture of the normal follicle. Cer- 

 tain subsequent observers, wondering how the ovum could be 

 freed from its apparently secure moorings, were led to conjecture 

 that there is a total desquamation of the granulosa— an error in 

 which they were confirmed by the fact that for lack of the proper 

 stages they did not see the mechanism for cutting off the ovum 

 described by Bischoff, but did see, on the other hand, the com- 

 plete dissolution of the granulosa, in follicles which we now know 

 to have been atretic. 



THE FRESHLY RUPTURED FOLLICLE 



Four animals of my series contained follicles which had rup- 

 tured very recently. One of these sows had shown the first 

 signs of heat at some time between thirteen and twenty-two 

 hours before killing, another between sixteen and thirty-nine 

 hours before killing, and the other two were in the second or 

 third day of oestrus (probably the second). As we have shown 

 on page p. 132, rupture of the follicle occurs on the first or second 

 day of oestrus. In all four of these cases, unfertilized ova were 

 found in the tubes, there having been no copulation. 



Apparently the act of rupture begins by the production of a small 

 slit in the exposed part of the follicle, through which the ovum 

 escapes to enter the tubal fimbria (figs. 8 and 9). A varying 

 amount of the follicular fluid, usually a considerable portion, is 

 extruded with the egg, and the follicle collapses as the volume 

 of its contents suddenly lessens. It seems that an important 

 part in this collapse must be taken by the fibers of involuntary 

 muscle which lie in the theca externa; through their contrac- 

 tion the follicle is greatly diminished in all dimensions. At the 

 point of rupture, the muscle fibers draw the theca externa away 

 from the torn area, and the result is a slight eversion of the 

 wound, through which the theca interna and granulosa protrude, 

 forming a small reddish papule 1 mm. or less in diameter, 

 the so-called stigma (fig. 12). The eversion of the inner layers 



