588 
J. BRONTE GATENBY. 
phases the nucleus does not give us any very characteristic 
evidence we will turn to the cytoplasmic bodies. In PL 31, 
fig. 11, is drawn a cell thought to be an oogonium. I believe 
it to be such for the same reasons which I brought . forward 
for fig. 6 of PL 30. The cytoplasmic cloud does not differ 
markedly from many another example known to be a male — 
it contains the same lumps and is isolated to one side of the 
nucleus in the same way. Pl. 30, fig. 6, is thought to be a 
later stage. A Nebenkern has appeared. Fig. 10 of PL 31 
is a still later stage — the nucleus is losing its chromatin loops, 
while the mitochondrial mass looks less granular and more 
flocculent. At one side is an undoubted Nebenkern, but of a 
slightly different type, the rods being straighter. Fig. 10 of 
PI. 31 really corresponds to the same stage in the male drawn 
PL 33, fig. 31. 
I have already mentioned what great variation was found 
in the appearance of the male cells. This, I think, applies 
even more strongly to the case of the female cells, but a 
difference which seems to exist between all the female cells 
and the male cell is that in the latter the mitochondria are 
from the first to the last granular and comparatively large, 
while in the former the mitochondria, even if at first 
granular, rapidly become flocculent and lie like a cloud, as 
shown in PL 31, figs. 10 and 12, and in later stages in PL 30, 
figs. 3, 5, 7, Pl. 31, figs. 9, 13, 14. Later, the mitochondria of 
the egg seem to become granular, spherical, and often some- 
what larger than the male, but there is then no possibility 
about making a mistake as to the sex at this period. 
Pl. 31, figs. 12 and 9, show stages in the mitochondria. 
In the former figure, which is drawn one-half the size of 
fig. 10, the mitochondria are dispersing, not, however, from a 
centre as they are in fig. 9. In this figure there is a 
centre from which flocculent masses of mitochondria radiate. 
It will now be clear that the most certainly diagnostic 
evidence for difference between the oogonium and spermato- 
gonium is to be found in the mitochondria, which early behave 
differently in either sex. 
