CYTOPLASMIC INCLUSIONS OF THE GERM-CELLS. 589 
The Fate of the Mitochondria and Nebenkern in 
the Egg. 1 
The flocculent mitochondria gradually become dispersed 
somewhat unevenly throughout the cytoplasm as shown in 
PI. 30, figs. 3 and 7, and in PI. 31, fig. 9. If these mito- 
chondria be examined it will be found that they consist of 
masses of exceedingly fine grains (PI. 31, fig. 13). In later 
stages these grains become here and there mixed up with 
la.rger granules as shown in PL 31, fig. 14. In a still later 
stage no flocculent masses remain, there being now only large 
mitochondria. The latter seem to be derived from the floccu- 
lent masses as shown in PI. 31, fig.* 14, and in different eggs 
are of different sizes as is the case with the mitochondria of 
the male. Soon after this, vacuoles appear in the cytoplasm 
and the mitochondria lie in the trabeculas between these 
alveoli (PI. 31, fig. 16). Yolk disclets sooner orlater partially 
fill these spaces (PI. 31, fig. 16, Y.), but are not to be con- 
fused with the mitochondria at any stage. In later stages 
the cytoplasm becomes divided into a cortical layer without 
yolk vacuoles, and an inner layer like that drawn in PL 31, 
fig. 16. 
After the stage drawn in PI. 31, fig. 10, the Nebenkern 
seems generally to become obliterated by a curtain of mito- 
chondria, but as shown in Pl. 30, fig. 5, it may still be quite 
plain. Its subsequent fate is difficult to follow, for it cannot 
be found in every oocyte. In PL 31, fig. 22 (at X.N.K.) are 
round bodies which are almost certainly separate parts of the 
Nebenkern. I have found many oocytes showing these ring- 
like structures. 
In later stages there appears a clearer zone near one side 
of the nucleus, and in this zone appear several blocks of 
darkly-staining matter as shown in Pl. 31, fig. 18; the two 
left-hand pieces are drawn at a high power in PL 30, fig. 8, 
and consist of more or less solid matter, which generally con- 
tains cavities. The nature of these structures and their con- 
1 See Addendum B. 
