156 GEORGE W. CORNER 



ties. Again, trauma at the time of killing does not explain away- 

 all the haemorrhages; for instance, in those cases in which among 

 a number of solid, bloodless corpora lutea several days old, one 

 or two others are found distended with dark clotted blood to a 

 size exceeding the normal corpora. I feel that the present evi- 

 dence indicates that haemorrhage into the corpus luteum of the 

 sow, while not uncommon, is the exception rather than the rule, 

 and is of no anatomical or physiological importance. Indeed, 

 the arrangement of the follicle seems well adapted to prevent 

 any considerable loss of blood into the cavity, for the tiny ves- 

 sels at the place of rupture are promptly directed outward toward 

 the peritoneal cavity, while the follicle is provided with smooth 

 muscle, which keeps the walls tensely contracted, even after 

 rupture. When small haemorrhages occur, undoubtedly they 

 are readily resorbed, and the corpus luteum then goes on to de- 

 velop normally. When great enough to distend the follicle and 

 compress the growing wall, inhibition of corpus luteum forma- 

 tion presumably occurs, and we have here one of the causes of 

 corpus luteum cysts, which are very common in swine. 



INVASION OF THE GRANULOSA 



The next stage is represented by seven animals in my collection, 

 all of which were killed during oestrus, as normal ova were found 

 in the tubes. Moreover, four of them were observed during life, 

 and were actually seen to be in the second or third day of 

 oestrus. In three, copulation had not occurred; in three others, 

 fertilization had taken place, the ova showing the pronuclei 

 approaching conjugation; and in the seventh, the ova were seg- 

 mented into two, four and six blastomeres. 



The first sign of an advance upon the previous stage consists 

 of the breaking-down of the membrana propria, at first at the 

 apices of some of the folds, later over the entire follicle, so that 

 the former sharp line of division between granulosa and theca 

 interna is no longer present (fig. 14). Wherever the membrana 

 propria is disappearing, slender spindle-cells are seen to be 

 insinuating themselves between the still closely packed granu- 



