No. 2.] CENTROSOMES IN THE ANNELID EGG. 203 
continue to grow and press against one another, still including 
the female centrosome, whose position is indicated by the point 
of convergence of the rays (Figs. 35-38). The latter gradually 
become fewer and less distinct and finally vanish altogether. 
I believe that the rays of the female aster, which were so 
strongly developed in the earlier stages of the reconstitution of 
the pronucleus, become resolved into a cytoplasmic network, 
which in part may be incorporated into the system of rays 
belonging to the male amphiaster. I have seen during this 
period of disintegration a number of extremely minute asters 
(secondary or tertiary mechanical centres) between the periph- 
ery of the egg and the female pronucleus. 
The vesicles completely coalesce to form a female pronucleus 
similar in size and general appearance to the male pronucleus 
with which it later comes into close apposition (Fig. 39). 
These phenomena suggest the interpretation that the chro- 
mosomes at the inner pole of the second maturation-spindle are 
not only drawn toward the egg-centre, but that the latter con- 
tinues for some time to be the centre of attraction and thus 
groups the chromosomic vesicles about itself and holds them 
together. The disappearance of the female aster is simultane- 
ous with the coalescence of the vesicles. After their fusion 
there is no further need of this attractive influence and the 
aster disappears. Apparently, also, the male centres exert an 
attractive influence upon the group of vesicles as a whole, 
though it is not ordinarily strong enough to dissociate the 
group by drawing the nearest vesicles to the centre in advance 
of the others. In one case, however, this phenomenon seems 
actually to take place (Fig. 36). 
But, whether the grouping of the vesicles is a function of the 
female centrosome or not, it would seem utterly preposterous 
to presume that this waning structure suddenly emerges from 
the midst of the fusing vesicles, divides, and unites with the 
male centrosomes. 
Before the two pronuclei meet, the vesicles of the female are 
completely united and resemble the male pronucleus in all 
respects, though they always lie on the side toward the polar 
globules. The two pronuclei come together and flatten against 
