320 WHEELER. EVOL. IL: 
gradual metabolism of the deeply colored yolk into pale yellow 
protoplasm. 
As the yolk spheres are much smaller in Doryphora than in 
Llatta, mutual pressure does not make them so clearly polygonal. 
Though granular, the protoplasm, which is spread in such a 
thick layer over the surface of the yolk, contains none of the 
bacillar bodies so easily demonstrated in 4éatfa. It is of course 
possible that in the beetle’s eggs they may be present, but of 
much smaller size and of spherical shape like those found in the 
Lepidopteron Pzervs. 
The chorion in Doryphora is thick and somewhat leathery, 
though easily torn with the dissecting-needles. It seems to re- 
semble in every way that of Lzza as described by Graber (15). 
The surface layer of protoplasm secretes a very delicate and 
structureless vitelline membrane, which in the younger stages 
is closely applied to the surface of the egg. Soon after the 
formation of the ventral plate it is loosened and stands off from 
the surface. Besides some clear, irregular patches on the sur- 
face of the chorion I have seen no structures which could be 
interpreted as micropyles. 
As there are strong reasons for supposing that the cleavage 
nucleus is situated in the very centre of the egg while dividing, 
the copulation of the pronuclei must take place along the radial 
line joining the centre of the egg to the point where the polar 
globules are formed. As I possessed no eggs immediately after 
oviposition, the phenomena of pronuclear conjugation, which 
could probably be more favorably studied in the eggs of Dory- 
phora than in 4latta, on account of the perfect and even sec- 
tions obtainable, were not observed. 
The first stages after the one given in Fig. 60 which I have 
been able to find in my material showed the division imme- 
diately following the first and second divisions of the cleavage 
nucleus. As the few nuclei were all near the centre of the egg, 
and as Graber has found the cleavage nucleus is the centre of 
the very similar eggs of the allied Zzza, I feel justified in believ- 
ing that this is the point at which the first division occurs. The 
products of the cleavage nucleus go through karyokinesis, but 
owing to their much smaller size the process is much less dis- 
tinct than in A/atta. In eggs stained with borax carmine, the 
cytoplasm of each cell appears as a delicate pink cloud among 
