A Study of the follicular Epitheliuui from the Ovary etc. 631 
surface ot‘ the oöcyte (Figs. 2 VI, 3 and 4). The nuclei increase in 
size and change their shape until they become nearly spherical (Fig. 5). 
The nuclei retain their spherical form for some little time as those 
of this shape can be found predominating in more than one chamber 
of the same tubule. Next the nuclei begin to elougate, the lengthe- 
ning taking place now only in a direction radial to the oöcyte (Fig. 10): 
it will be observed tliat, after this change in form begins, the future 
growth of the cell and its nucleus is all in this same direction. The 
epithelial cells of the older chambers while mach larger than those 
we are at present considering, show this as a great increase in length 
only so that cells of an old chamber occupy but little more space 
along the surface of the oöcyte than do these younger ones (compare 
figure 6 or 10 with 16). The elongated nucleus with rounded ends 
is typical of all the stages in the growth of the epithelial cells from 
now until much later when the cells begin to shorten; this other 
change will be described later. This change in shape of the epithe- 
lial cells in passing from the young to the old chamber has been 
noticed in a number of other insects. Düring this increase in size 
of the epithelial cells their structure undergoes but little change. The 
chromatin granules increase greatly in number but not in size. In 
the first fully formed chamber the small nuclei generally contain each 
a single nucleolus, which in some nuclei appears to be composed of 
a few darkly staining pieces held together by a lighter staining mass. 
When staincd with safranin and well washed these darker portions 
of the nucleolus are the only parts retaining the stain. In the next 
oldest chamber there is generally a single nucleole but it often appears 
broken up and more irregulär in outline than in the younger ones. 
In the fourth chamber from the distal end each nucleus contains, as 
a rule, two nucleoli, but there may be more. 
When the nuclei of the epithelial cells change from a spherical 
to an elongated form, cell division occurs very frequently, and, from 
this stage until division ceases, mitotic ligures are much more abundant 
than in the very early stages. In all the later stages there are in 
each chamber very many more epithelial cells than in the younger 
ones; the greater number of mitotic figures seen in these later stages 
is not all due to this increase in the number of cells but also to the 
greater number of those which are dividing. One may often lind 
older chambers in which but very few mitotic ligures are seen, but 
generally this is not the case. Before the elongation of the epithe- 
lial cell nuclei has gone far an increase in the frequcncy of cell 
