108 H. H. NEWMAN. 



of follicular growth. Full grown ovocytes, for example, are in- 

 variably to be found in follicles of stage 10 (Fig. 10), while mature 

 or maturing ovocytes are found only in follicles of type 1 1 (Fig. 

 ii). It is fortunate for the student of ovogenesis that the 

 condition of the follicle furnishes such an accurate index of the 

 more important ovocytic changes, since it enables him to search 

 through a large amount of material wdth low powers of the 

 microscope and to detect readily certain follicles which he may 

 examine with the assurance that he will find the desired stages of 

 ovocytic or nuclear development. Hence the following very 

 brief account of folliculogenesis is offered largely for the purpose 

 of rendering the subsequent ovocytic and nuclear history more 

 easily followed by the reader. 



Stage I (Fig. i). The primordial follicle is just in process of 

 establishment. Frequently nests of young ovocytes are found 

 to be surrounded by primary follicular cells, giving the impression 

 of several ovocytes in a single follicle. This is not really a 

 pluriovular follicle but simply a stage prior to the completion 

 of the establishment of the true primordial follicle. It is, how- 

 ever, positively the only condition in the entire process of 

 ovogenesis in which I have found anything that might be looked 

 upon as a fusion of follicles. The diameter of the follicle at the 

 time when the ovocyte is surrounded with follicle cells averages 

 about .03 mm. 



Stage 2 (Fig. 2). The single layer of primary follicle cells 

 takes the form of a simple cubical epithelium, sharply cut off from 

 the capsule of stroma cells. Both ovocyte and follicle cells have 

 grown considerably, for the average diameter of follicles of this 

 stage is about .1 mm. 



Stage j (Fig. j). The simple epithelium of the follicle becomes 

 compound. The figure shows a three-layered condition. Fol- 

 licles at this stage have an average diameter of about .15 mm. 



Stage 4 (Fig. 4). There is a strong tendency at this stage for 

 the follicle to become elongated on account of the more rapid 

 proliferation of the cells at the two ends. This condition is 

 usually accompanied by an elongation of the ovocyte as shown 

 in Fig. 15. This phenomenon is of such frequent occurrence 



