162 DELLA DRIPS 
of great numbers of red granules in the protoplasm of the luteal 
cells. This phase embraces a period dating from the bursting 
of the follicle and covering the entire period of pregnancy. From 
a point of time very shortly after the bursting, the protoplasm 
of the luteal cells shows these red granules which become more 
and more abundant until they seem to reach a crisis of abundance 
when the organization of the luteal structure is about perfected, 
which is not until the placental swellings have reached a length 
of about 8.5 cm. From this time on the granules seem very 
gradually to decrease in number in the cells until parturition, 
when there is a sudden considerable reduction in their number. 
Some are found in the cells, however, even as late as the fourth 
week after parturition. Second, the phase characterized by the 
presence of many lipoid droplets in the protoplasm of the luteal 
cells. This phase begins sometime before parturition and lasts 
for about six weeks afterward. About the fourteenth day of 
pregnancy when the placental swellings in the uterus measure 
1.5 em. to 2 em. in length, the lipoid droplets usually begin to 
make their appearance at the periphery of the luteal cells next 
to the capsule of the corpus luteum. ‘They increase in number 
until at the time of parturition, they are quite noticeable in the 
cells, being found scattered all through the protoplasm among 
the red granules. After parturition, there seems to be a more 
rapid increase in the number of lipoid droplets, which coincides 
with the sudden decrease in the number of red granules pre- 
viously noted. With this increase in lipoid content the cells 
which, from the beginning, have been growing constantly larger, 
seem to begin to hypertrophy more rapidly. The luteal cells 
are largest and contain the greatest amount of lipoid about six 
weeks after parturition. In two more weeks practically all the 
lipoid has disappeared from the cells and they are beginning 
to show evidences of degeneration. Third, the phase of regres- 
sion. This period begins about eight weeks after parturition and 
lasts for four weeks. By the last of August the corpora lutea 
have disappeared from the ovaries. This phase is characterized 
by a fatty degeneration of the luteal cells by an increased 
vascularization and a connective-tissue invasion. 
