No. 2.] BLATTA AND DORYPHORA. 311 
In more than a hundred eggs which I sectioned from capsules 6 
to 24 hours old I found the greater number in the polar globule 
stage and all the remainder, with two exceptions, in the stages 
just before, during and after the division of the cleavage nu- 
cleus. In the two exceptions which I describe and figure I 
found what I take to be the pronuclei. The arrows in the 
figures point in the direction of the long axis of the egg, only 
the circumnuclear portions of which are represented. 
In Fig. 19 the female pronucleus is about one-third the dis- 
tance from the cephalic end instead of being in the middle of 
the egg where the polar globules are formed. It is no further 
from the dorsal surface than the female pronucleus in Fig. 17, 
but is much larger. Hence I believe it has travelled up along 
the dorsal surface to meet the male pronucleus (Fig. 19 ¢ pz), 
which has advanced through almost the whole dorsoventral 
diameter of the egg. The female pronucleus exhibits the usual 
coiled chromatin filament. The male pronucleus is granular, of 
somewhat irregular outline, and surrounded by vacuolated pro- 
toplasm. It is rather deeply stainable in borax carmine. In 
this Fig. 19 the pronuclei are of very different size, and not- 
withstanding the male pronucleus has passed through three- 
fourths of the dorsoventral diameter, a distance of ? mm., it has 
not increased much in volume when compared with the mass of 
the long though attenuated head of the spermatozoon from 
which it originated. No astral radiation could be seen surround- 
ing these pronuclei. In Fig. 20 we have what I take to be the 
two pronuclei conjugating The smaller presumably male portion 
of the compound or cleavage nucleus is larger than the male pro- 
nucleus in Fig. 19. The place of union is about the middle of 
the homogeneous yolk, z.e/ about one-third of the dorsoventral 
diameter from the back of the egg. The nuclei of Fig. I9 
would probably have fused at a point near the dorsal surface 
one-third the distance from the cephalic to the caudal pole, but 
the paths of these two nuclei were undoubtedly aberrant. My 
observations on single female pronuclei and cleavage nuclei 
found at various points along the median dorsoventral diameter 
lead me to conclude that the middle of the homogeneous yolk is 
the normal point of conjugation. I have represented (Fig. 18) 
another female pronucleus from near the point of fusion because 
its structure is different from that of the other female pronuclei 
