CYTOPLASMIC INCLUSIONS OF THE GERM-CELL8. 591 
to think that modified representatives of Nebenkern and mito- 
chondria may be found in the cytoplasm of the yolk cell. 1 
After some time the yolk cells become exhausted completely, 
and the wide reticulum breaks up and the nuclei float out into 
the lumen of the ovotestis diverticulum as shown in Text- 
fig. 3, i, N.C.N., E.N.C . These nuclei do not degenerate, as 
might be supposed. They lie there in the midst of a mass of 
live cells and degenerate yolk, and seem to undergo further 
changes which need not detain us at present, but I should 
say that it is my firm opinion that these nuclei regain a cyto- 
plasm and become spermatocytes. 
Description of the Scheme on PI. 29, fig. 1. 
In this figure I have united my final conclusions concern- 
ing the processes which go on in the various regions of diver- 
ticulum of the ovotestis of Helix. All cells have been drawn 
in to scale with a camera lucida, and in the majority of cases 
are the same as those on the other plates drawn at a higher 
power. Great care has been taken to show the germinal 
epithelium in its true state; thus, for instance, the region of 
the right lower edge marked by the Homan figures is the 
same kind as that drawn in Text-fig. 3, i. The left lower 
half appears also in Text-fig. 2, i, and so on. 
In the following description, after mentioning each series 
of cells, I will indicate where they are drawn at a higher 
power in the other plates. If not the identical cell, I will 
show this by adding the letter W. to the bracket. 
The Genesis of the Egg. 
A =■ Differentiating germinal cell embedded in yolk cells 
(Pi. 31, fig. li-ir.). 
B = Young oocyte (PI. 30, fig. 6- TP). 
C — Older oocyte (PI. 30, fig. 3, 7, etc.- IF.). 
D — Older oocyte (PI. 31, fig. 9-TF.). 
1 More work on a dozen species of Pulmonates shows that the true 
yolk cells do not contain mitochondria or Nebenkern. 
