No. 2.] BLATTA AND DORYPHORA. 317 
has assumed a different appearance. It is no longer distributed in 
the long, even, much convoluted filament, but has broken up into 
several spherules which stain more deeply. One or more large 
vacuoles are to be found in each one of these nucleoli, or masses 
of chromatin, which under a high power seem to hang suspended 
in the meshes of the nuclear reticulum in the same manner as 
the homologous bodies of Alatta. From the time of its first 
formation till the ovum has attained a considerable size, the fol- 
licular epithelium is columnar with its elongate nuclei directed at 
right angles to the long axis of the egg. Later the epithelium 
flattens, and the nuclei become kidney-shaped, with their long 
axes tangentially directed to the surface of the egg and their 
hili directed inwards. 
The yolk first makes its appearance in the form of numerous 
granules. In no case have I seen a degeneration of the follic- 
ular epithelium to form yolk. The large granular yolk spheres 
soon make their appearance. As these bodies are much smaller 
than, but in other respects very similar to, those in A/a/ta, I 
have given little attention to their study. Though the proto- 
plasm is reduced to a very delicate reticulum by the great ac- 
cumulation of yolk spheres, there remains till the formation of 
the blastoderm, contrary to what I have observed in 4/atta, a 
thick layer of finely and evenly granular protoplasm, which en- 
velops the whole egg and is equivalent to Weismann’s Kezmhaut, 
though it is present from the first appearance of the yolk in the 
form of spheres, and does not originate just before the forma- 
tion of the blastoderm, as in several of the insects studied by 
Weismann (47). The thick surface layer stains pale pink in 
borax carmine, and is quite distinctly marked off from the retic- 
ulate yolk-charged protoplasm of the interior of the egg. 
After the nuclear filament has become metamorphosed into 
the spherical vacuolated masses above described, the nucleus 
moves from the centre of the egg to the surface, travelling along 
a line at right angles to the polar diameter of the egg. It thus 
reaches a point midway between the poles, taking the same 
position as the germinal vesicle of A/atta. During its migra- 
tion the karyoplasm becomes amoeboid, and except at its outer 
surface retains its irregular form even after taking its position 
right under the follicular epithelium. The outward directed 
face becomes excavated, the rest of its surface remaining con- 
