128 
J. T. CUNNINGHAM. 
liform structure. The divergence of the chromatic groups is 
due to the contraction of the achromatic fibrils towards the 
polar stars. These stars take no part in the edification of the 
daughter nuclei which are formed by the gradual diffusion of 
the chromatin through the achromatic substance. No convo- 
lution stage occurs in the reconstruction. The mature daughter 
nuclei have the same structure as the mature pronuclei (see 
figs. 11, 12, 13, PL X). 
Flemming observed a longitudinal division of the chromatic 
loops in cells but could not prove that this division was con- 
cerned in the division of the equatorial plate formed by the 
loops. Van Beneden has proved that the latter phenomenon 
is due to the former. It has struck me that here lies the 
solution of the controversy between Strasburger and Flemming 
pointed out in a previous essay. 1 The division of chromatic 
elements in the equatorial plane, affirmed by Strasburger and 
denied by Flemming, is probably the same thing as the longi- 
tudinal division of the chromatic loops described by the latter. 
The division of the vitellus into two blastomeres is not due 
to a complete constriction. A furrow appears on the outside 
of the vitellus, but division is completed by a cell-plate” such 
as that described by Strasburger in plants. This cell-plate is 
a homogeneous layer formed from the intermediate achromatic 
fibrils and in its centre a limiting surface appears which 
separates the two blastomeres. The rest of the intermediate 
fibrils are assimilated by the vitellus. 
The first two blastomeres divide in exactly the same way. 
Only four chromatic loops are present at the equator of each 
spindle. 
Theory of Fecundation. — Of the four chromatic loops 
in the first segmentation-spindle two are male and two female. 
Similarly every cell formed from the two first blastomeres, 
and each of these blastomeres themselves, is hermaphrodite. 
Therefore ovarian cells destined to become ova are originally 
hermaphrodite, and likewise the cells of the testis destined to 
become spermatozoa. But an ovarian cell in becoming an 
1 This Journal, 1882. 
