62 LEO LOEB 
increase in the size of their nuclei. The connective tissue around 
the medullary canals is relatively dense. In the granulosa, theca 
interna and in the ordinary connective tissue stroma mitoses are 
frequent. 
3. The ovaries of guinea pigs eighteen days old are larger; the 
follicles also have increased in size. Small and medium sized and 
in proportion to the as yet small size of the ovaries, relatively 
large follicles are present. In some of the follicles degenerative 
processes appear at this time, but the extent to which such changes 
have taken place differs in the ovaries of different animals. In 
the ovaries of some guinea pigs no degeneration of the granulosa 
has as yet taken place. In the ovaries of another guinea pig a 
few follicles showed a trace of granulosa degeneration, while in 
another follicle the granulosa degeneration was pronounced. 
In the folliclesof some ovaries we find even a beginning ingrowth 
of connective tissue into the follicular cavity, and in one case a 
cavity of a follicle was filled with loose connective tissue. The 
majority of the follicles are in a good condition; their cavity is 
larger than at the preceding stage and the interna is better devel- 
oped and consists of more rows of cells. Mitoses are present in the 
theca interna and in the granulosa. The connective tissue be- 
tween the follicles is a little more fibrous, and around certain 
blood and lymph vessels it is somewhat edematous and rarefied. 
4. In the ovaries of guinea pigs twenty-eight days old the major- 
ity of follicles are in good condition and non-atretic; they are of 
small and medium, but not yet very large size. In some ovaries 
hardly any degeneration of follicles is visible; in others we see some 
follicles which have not yet attained their full size (corresponding 
to the as yet small size of the ovaries), presenting various stages of 
granulosa degeneration. In some follicles the granulosa has been 
entirely destroyed and connective tissue begins to grow into the 
cavity.* In some cases we find quite atretic connective tissue 
follicles. In some small and medium sized follicles the ova may 
undergo (probably amitotic) nuclear division and a corresponding 
segmentation of the cytoplasm, the granulosa being still intact. 
