A Study of the follicular Epithelium from the Ovary etc. 637 
these dark cells the nucleoli were smaller tban in the normal ones. 
In many sections of different kinds of tissue one may find cells and 
nuclei that are, without any apparent reason, darker than others. In 
these cells we are describing the difference was generally very great 
and, occurring in certain chambers and not in others, we are lead 
to believe the greater susceptibility of some cells to stains is due to 
certain activities of the cell and nucleus. 
The epithelial cells continue to lengthen as the oöcytes increase 
in size and finally attain a great length each becoming a very long 
and narrow cell. The nucleus is only a little narrower and not much 
shorter than the cell. In structure neither the cell nor its nucleus 
shows any marked changes, in fact the only difference noticed is a 
little more irregularity in the sliape of the nucleoli. Activity of the 
cells is still shown in the presence of vacuoles and offen a striation 
at their free ends (Fig. 21). Mitosis practically ceases before the cells 
attain their maximum length. As will be shown later the oöcytes 
still increase somewhat in size; this would mean an increase in the 
number of the epithelial cells were it not for the great change in their 
shape which now begins to take place and to continue throughout 
the further growth of the oöcytes. 
The peculiar forms and markings of the eggs of the Phasmidae 
has offen been described. Diapheromera does not have a strikingly 
peculiar egg, but one feature has offen been noted. Partiallv down 
one surface, but not exteuding from end to end of the egg, is a 
raised portion or ridge. It is necessary to call attention to this be- 
cause at this region the epithelial cells are considerably longer than 
at any other part (Fig. 20). This is due to the greater thickness the 
chorion will have at this place. None of the cells drawn have been 
taken from this chorion-forming part but attention is called to the 
cross section (Fig. 20) to sliow that even in places other than where 
the ridge is to be formed, there is a great Variation in length of the 
epithelial cells in the same chamber. 
While secretorv activity does not cease when the epithelial cells 
attain their maximum length it does, later, assume another phase, 
the formation of the chorion. Until this stage is reached there is 
nothing in this connection different from wliat has already been 
described. There is however, beginning at this stage, a marked 
change in the shape of the epithelial cells. The last epithelial cells 
described (Fig. 21) were very long and narrow, they formed a row 
each cell of which, excepting those at the ends of the chamber, stood 
Archiv f. Zellforschung. III. 42 
