628 
ffm. S. Marshall 
Most of the material used in tliis work was preserved in Flem- 
ming, botli weak and strong, altbougli Petrunkewitsch and Subli- 
mate Solutions were also used. Flemming’s triple stain and iron- 
haematoxylin were used more tban any otlier stains for the sections, 
but staining was not restricted to tliese two. For whole mounts 
Delafield's haematoxylin gave good results especially when tbe 
objects were overstaiued and then waslied out with acid alcohol. 
Just before the walking-stick begins to lay its eggs there is, in 
a majority of the ovarian tubules, a great ditference in size between 
the proximal oöcyte and the others (Marshall and Severin [19] 
fig. 41). After the largest oöcyte has beeu ejected from the tubule 
tliis difference in size in the remaining ones is not for some time so 
marked. Before the iusects liave become mature eacli tubule shows 
the entire chaiu of oöcytes in a regulär gradation in size from the 
oldest and largest, proximal, up to the two to four youngest which, 
situated near the distal eud of the tubule, are of nearly the same 
size (Fig. A). As soon as the large proximal oöcyte has passed out 
the next one in the tubule, now proximal, must begin a period of 
rapid growth necessitating a great activity in the follicular epitlie- 
lium. 
A longitudinal section tlirough an ovarian tubule shows a long 
narrow terminal filament of a nearly equal thickuess throughout; 
proximal to this is a small terminal chamber separated from the 
terminal filament by a layer of darkened protoplasm, there is also 
a slight iudentation in the tubule at this point (Fig. 1, between t. f. 
and t. c.). Within the terminal chamber are two different kinds of 
nuclei; smaller ones very similar in structure to those within the 
terminal chamber and also those of the epithelial cells, and the 
larger nuclei of the young oöcytes nearly circular in outline and diffe- 
rent in structure from the others. Proximal to the terminal chamber 
are the oöcytes the two or three youngest of which are generally 
equal, following tliese they gradually increase in size. The oöcytes 
show a linear arrangemeut except that in some tubules two of the 
youngest lie side by side Daiber (6). A study of a longitudinal 
section of a tubule shows that all the oöcytes do not lie in separate 
chambers entirely cut off from the others and completely surrounded 
by an enclosing layer of epithelial cells. Figure one, which gives 
the terminal chamber and the two youngest oöcytes of a tubule 
shows that there are very few epithelial cells (nuclei here as but 
lew cell bouudaries can be distinguished) surrounding either of tliese 
