362 G, HAROLD DREW 



degenerate, and eventually become dissolved, leaving the gran- 

 ules behind. 



Fig. 2 shows the condition at the fifth day. The degeneration 

 of the ovarian tissue is practically complete, though traces of the 

 ova still remain : this tissue is surrounded by layers of oval fibro- 

 blasts, and the fibroblasts in the neighborhood are still dividing 

 and migrating towards the cyst wall. Blood corpuscles are mak- 

 ing their way into the cyst between the fibroblasts forming its wall. 



The subsequent changes occur more slowly. The fibroblasts 

 forming the innermost layer of the cyst wall remain unchanged 

 for some time, but those forming the outer layers regain the typi- 

 cal elongated spindle shape, of the resting fibroblast. Then, after 

 a period varying from eighteen to twenty-five days from the im- 

 plantation, the fibroblasts in immediate proximity to the degen- 

 erated ovarian tissue alter their appearance. The nuclei become 

 rounder and the cytoplasm of each joins up with its neighbor, 

 forming a faintly staining and somewhat indefinite continuous 

 layer (fig. 3) . Sections of a little later date show this layer more 

 defined and also a change in the character of the nuclei. An ag- 

 gregation of the chromatin resembling a nucleolus appears, and 

 from this thin strands of chromatin radiate to the periphery. No 

 cell walls are visible between the nuclei, which appear to have 

 reverted to an embryonic type. Fig. 4 shows this condition, the 

 contents of the cyst are surrounded by a continuous layer of nu- 

 clei with definite nucleoli, and these nuclei are embedded in a mass 

 of cytoplasm having no dividing cell walls. 



In the course of a few days these nuclei again alter in shape 

 (fig. 5), they become smaller and more oval, and the nucleoli dis- 

 appear. The surrounding cytoplasm becomes more definite, and 

 stains deeper, and a distinct boundary or basement membrane 

 appears between it and the layers of fibroblasts. 



Shortly after this, long slender cilia appear from the inner bor- 

 der of this layer of cells (fig. 6). These cilia are very delicate and 

 at first irregular in length, varying from a length about equiva- 

 lent to the depth of the cells to. more than twice that amount. 

 The date of the appearance of cilia varied from 21 to 32 days, 

 and seems to have some relation to the amount of ovarian tissue 



