70 B. F. KINGSBURY 



the indifferent or follicle cells rather than directly between 

 stroma and developing ovum. 



During the first three months after birth great irregularity 

 characterizes the growth changes of the parenchyma within the 

 interior of the cat's ovary, causing morphological relations of 

 considerable complexity and irregularity, which are differently 

 interpreted by myself (in the previous paper) and by v. Wini- 

 warter and Saimont ('08). The series during this period indicate 

 that it is one of marked growth of the stroma as well as of the 

 parenchyma so that it seemed to me the irregular and atypical 

 structures expressed, morphologically an attempt at follicle 

 formation during rapid growth of the ovary as a whole. While 

 the stroma contributes to the general complexity, a relation to 

 the masses of indifferent cells and irregular follicles, is neverthe- 

 less evident, as appears in some of the photographs illustrating 

 the previous paper. 



Many of these follicles develop into the large, irregular pluri- 

 ovular follicles previously mentioned. These possess very defi- 

 nite thick stromal thecas, including, in fact, most of the stroma 

 in this zone of the ovary. 



The period of developing medullary follicles is likewise the 

 most complex in the distribution of the interstitial cells, which oc- 

 cur in smaller or larger masses in the midst of the stroma strands, 

 which show in general the same relation to the follicular masses 

 as does the stroma out of which they are developed. 



The zones occupied by the bulk of the interstitial cell groups 

 in four typical stages — 6 days, ca. 5 weeks, ca. 3 months, and 

 in the adult ovary — may be illustrated by figures 1 to 4, in which 

 the dense black of the osmic acid stained lipoid locates the in- 

 terstitial cells in which it is contained. 



It may be noted that the interstitial cells occur in the zone 

 where growth (of the indifferent cells) is apparently most active 

 — about the medullary cords, before and after birth; in the zone 

 of the medullary follicles, during their stages of growth, etc. 



Hence it might appear that they had to do particularly with 

 those growth changes and possessed a trophic 'function.' This 

 was the interpretation of Saimont ('05) and of v. Winiwarter 



