42? LEO LOEB 
corpora lutea are not very different from those found in the preced- 
ing period. This description holds good for instance for ovaries of 
a guinea pig extirpated ten minutes after complete delivery. 
Soon after delivery (usually within a few hours) the guinea pig 
is ready for a new copulation and ovulation, and after ovulation 
changes take place in the follicles which will be described later. 
The corpora lutea of the preceding pregnancy undergo no very 
marked changes within the next two days after delivery, although 
vacuolization of the lutein cells and degenerative changes in the 
nuclei show probably a slight advance; the lutein cells do not stain 
as well with eosin and appear pale. If copulation take place soon 
after delivery, a rupture of the mature follicles occurs within the 
succeeding six or ten hours; butif copulation be prevented by isolat- 
ing the female, ovulation frequently occurs, but does not need 
to take place within thirty-six hours after delivery. In several 
cases in which an actual copulation was prevented, in which how- 
ever the male was in contact with the female for a short time after 
delivery, the rupture of the follicles and the formation of new 
corpora lutea took place in the usual way. The changes inthe new 
corpora lutea within the first two days after delivery are the same 
as those described in a previous paper.? 
In three cases the lower part of the uterus or the vagina of guinea 
pigs were tied completely or incompletely towards the end cf 
pregnancy. This procedure led to the death of the fetuses, fol- 
lowed by expulsion of the dead fetuses in a case in which the occlu- 
sion had been incomplete. In another case the animal was killed 
by chloroform six days after the application of the ligature, and 
the fetuses were found dead; furthermore autolysis of the placenta 
had set in. In these cases especially the periphery of the corpora 
lutea of the preceding pregnancy showed vacuolization of the lute 
tein cells. The nuclei were shrunken or somewhat chromatolytic. 
Notwithstanding the degenerative changes visible in the corpora 
lutea, no new ovulation had taken place. From these and other 
observations it follows that delivery as such does not lead to far- 
2 The formation of the corpus luteum in the guinea pig. Journal American 
Medical Association, February 10, 1906. 
