2S0 H. M. KIXGERY 



occur here also (figs. 35, 30, 38). Usually however, oocytes in 

 stage 'c' are in primary follicles or in Graafian follicles of various 

 stages of development, up to the nearly mature primary oocyte 

 in the adult or sexually mature ovary (figs. 4. 5, 6, 40, and 7). 

 The maimer in which the oocytes penetrate the tunica albuginea 

 in lea\ing the germinal epithelimn and the formation of the fol- 

 licles have already been discussed (p. 3S4-3S5). 



An idiosome is not visible in stage a," and becomes well 

 niiirked only in cells of stage 'b.' Centrosomes are not infre- 

 quently clearly distinguishable in the idiosomes (figs. 32. 3S). 

 The mitochondriiil content of the cells of the germinal epithelium 

 is very scanty, and consists of a few granules close around the 

 nucleus (fig. 47). As the ooc5i:e begins to differentiate and grow 

 in size, the mitochondria increase in number and become located 

 cliiefty, perhaps, in the two ends of the cell, now somewhat o\"al 

 in shape (fig. 48). They are arranged near the nucleus and, as 

 differentiation proceeds, they tend to accumulate more in one 

 end or side of the cell, forming a more or less crescent-shaped 

 mass which marks the place where the idiosome develops (figs. 

 48 to 50). At about the begimiing of stage 'c' the mitochondrial 

 mass becomes dispersed a^id the granules are scattered quite 

 uniformly through the cytoplasm, accompanying the growth of 

 the cell (figs. 50, 51). There is no indication of a peripheral con- 

 densation of the mitochondria such as described for the cat's egg 

 by R. Van der Stricht ('ID. 



The oocytes remain in this stage "c* which somewhat re- 

 sembles von Winiwarter's 'dictye,' until ready for maturation. 

 There can be no doubt of tliis. Egg-cells have been followed in 

 their development up into mature or nearly mature Graafian 

 foUicles in sexually mature and adult ovaries, and the nuclei 

 are all in this phase (figs. 44 to 46, 7). The further develop- 

 ment of the ooc^'tes. the matimition divisions and the formation 

 of the mature ova. was not investigated, as bej'ond the scope of 

 this work. 



