190 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 
larger ones. In that case, less of the light passing through it 
will be reflected, and the eggs appear clear. A glance at Fig. 51 
shows that as a matter of fact the cytolyzed egg consists of 
large drops. It appears possible that the outflow of the clear 
drops in the cytolysis of the moderately unpigmented egg of 
S. purpuratus may correspond to the outflow of haemogiobin 
from the red blood corpuscles. It is to be noted that in this 
case it is unnecessary to assume a bursting of the surface layer 
of the red blood corpuscle. 
But from the point of view of our work, it is not necessary 
to venture upon a decision with regard to the lipoid controversy 
and cytolysis. We can observe directly that cytolytic sub- 
stances cause the chorion that surrounds the eggs to swell and 
then gradually to dissolve completely. It 1s necessary only for 
us to make use of this observation in order to understand mem- 
brane formation also. If we assume that in the cytoplasm of 
the egg itself there is present near the surface a substance that 
is identical with or closely allied to one of those in the chorion, 
we can understand that this must be made to swell and liquefy 
before the egg can develop. 
The swelling and solution of such a substance in the interior 
of the egg causes cytolysis, and hence it comes about that all 
cytolytic substances or reagents also produce an effect that 
leads to membrane formation, and hence to artificial partheno- 
genesis. 
