410 E. L. SHAFFER. 



on their role in normal processes. This is, however, beyond the 

 scope of the present work. 



The spermatogonial cysts which are in mitotic activity, stand 

 out very clearly in contrast with the resting cysts. This is 

 because of their lighter staining capacity; whether this is in 

 turn due to the partial disappearance of the mitochondria, could 

 not be ascertained (Figs. 2, 24). Buchner (1909) found that in 

 Gryllotalpa vulgaris the mitochondria disappear during or just 

 before cell-division. There are three possible explanations for 

 the partial loss of mitochondrial structure during mitotic ac- 

 tivity; (a) at this time the cytoplasmic volume is much greater 

 and hence the mitochondria are more diffusely spread; (b) the 

 dissolution of the nuclear membrane sets free a large amount of 

 karyolymph which perhaps dilutes the cytoplasm and obscures 

 the mitochondria; (c) the mitochondria may dissolve or become 

 chemically changed so that they are no longer recognizable as 

 such. At any rate, they soon appear in great numbers after 

 cell-division, so that their partial disappearance was apparent 

 and not real. 



2. Spermatocytes. In the spermatocytes at the beginning of 

 the growth period, the mitochondria are still in the form of dif- 

 fusely spread granules. There is a noticeable increase in their 

 numbers as the growth period progresses, which plainly indicates 

 that new ones are being formed (Fig. 6). Usually a denser 

 perinuclear zone of cytoplasm can be seen during the growth 

 period; the significance of this zone will be discussed later. 



As the late prophase approaches, the cytoplasm becomes filled 

 with numerous delicate threads deeply staining in hsematoxylin. 

 These are the filar mitochondria (chondrioconts) and they first 

 appear at this time, although there is a slight indication of deli- 

 cate granular threads in some of the earlier stages. The origin 

 of these threads could not be traced, but it is quite likely that 

 they are genetically related to the granules of the preceding 

 stages. In the first spermatocyte the mitochondria appear 

 diffusely spread when material has been fixed in Flemming's 

 fluid (Figs. 7, 8, 25, 25^). In Benda and Hermann material 

 the mitochondria agglomerate in dense irregular masses, still 

 showing their filar nature (Figs. 9, 26). The threads tend to 



