584 J. BRONTE OATEN BY. 
from much yolk. This cell is drawn in PL 31, fig. 17, at a very 
high power. 
The nucleus has the same general appearance as in Text- 
fig. 3 at S.P.P., though in the latter the chromatin lumps 
have not broken up so much as yet, as in PI. 31, fig. 17. 
Both these cells will ultimately divide and give rise to some 
secondary cells. The answer to the question why there 
should be differences in these two cells, however small, is 
that they originate from parts of the germinal epithelium 
which are in a different nutritive condition. Cells like these 
soon divide many times and give rise to bunches of spermato- 
gonia such as those shown in PI. 29, fig. 1, at the outer 2, or 
in Text-fig. 4 at iv. The connection between the yolk cell 
and the male progerminative cell is sometimes severed, some- 
times retained. 
Now, if attention be centred on the cytoplasmic cloud in 
these progerminative cells it will be noted that apart from the 
apparent denseness of the cytoplasm which causes the cloudy 
appearance one finds distinct granules. These are apparently 
the first signs of the mitochondria. The size and number of 
these granules are very variable. In PI. 31, fig. 17, they were 
very large and distinct. 
Towards the time when the lumps of chromatin in the 
nucleus have fragmented to form a fine clear granular struc- 
ture these cytoplasmic bodies become dispersed more and 
more from the zone from which they originally appeared. 
The chromosomes soon appear and a cell division takes 
place, the cytoplasmic bodies being visible and scattered here 
and there around the amphiaster. As far as I have been 
able to ascertain, these mitochondria do not lose their rounded 
shape during division. Such a series of divisions finally give 
rise to cells such as those drawn in Text-fig. 3 at S.P.iS. 
After a division is finished, and these secondary cells have 
regained their resting nucleus an examination of the cyto- 
plasm generally shows that two sets of bodies are present : 
one, the mitochondria, are scattered indiscriminately, the 
other is a dark structure lying close to the nuclear mem- 
