314 EDGAR ALLEN 
The corpora of the second set are larger than those of the first, 
are superficially located, and deep red in staining reaction. The 
cells are arranged in ‘cords,’ but their walls are not clear-cut and 
the cytoplasm has a blotchy appearance. The edges of these 
corpora lutea in section are clearly defined from the surrounding 
stroma. Theca interna cells as a distinct layer no longer exist. 
This set probably corresponds to the second ovulation before 
death, occurring at some time during the O period; therefore, 
seven to eight days previously. 
A third set of corpora lutea, less clearly defined from the 
stroma, red staining, and about the size of the first set, is present. 
The stroma has begun to invade their surfaces and the propor- 
tion of connective-tissue cells to luteal cells throughout has 
increased. ‘The record of this mouse shows an O period eleven 
to twelve days before death, so that this third set must be at 
least that old. There are a few cells clearly definable as inter- 
stitial in these ovaries. They are restricted in distribution to 
limited areas near the periphery. 
The oestrous period 
Animal *15 shows a typical oestrous condition. She had been 
examined for twenty-eight days previous to killing, in which 
time only three complete cycles had been recorded, making the 
average duration 94 days. Her oestrous periods were 6, 16 to 
17, and 28 days previous to death. Her last cycle was of five 
days’ duration. Her first and second cycles had long dioestrous 
intervals, seven to eight days in each case, while the other four 
stages required only three to four days. 
Upon opening the body cavity, the uterine and ovarian vessels 
showed some congestion, though less than that reported during 
the prooestrous period. The uterus was moderately distended, 
but less transparent. Gross examination shows the same condi- 
tions as found in the prooestrum to prevail, although to a less 
degree. 
The lumen of the vagina in cross-section is much folded and 
collapsed, as would be expected from the record of the examina- 
