ACTION OF THE SPERMATOZOON UPON THE EGG 239 
formation of a new cortical layer like the one which surrounds 
the unfertilized egg. But the effect of the previous treatment 
of the egg with hypertonic solution must have lasted, since 
otherwise the mere membrane formation by butyric acid in these 
blastomeres would have started a new development, but would 
also have caused the rapid disintegration of these eggs. What 
was the irreversible effect of the treatment with hypertonic 
sea-water? Certainly not the presence of centrosomes and 
astrospheres, since in the next paragraph we shal! show that if 
the parthenogenetic eggs are fertilized while they are still in 
possession of centrosomes or astrospheres, they perish. On the 
contrary these eggs which developed normally after artificial 
membrane formation had lost the centrosomes and astrospheres 
they had possessed immediately after the treatment with the 
hypertonic solution. 
We have stated in a previous chapter that the rate of oxida- 
tions is increased six times by a spermatozoon. In eggs treated 
for two and a half hours with hypertonic sea-water the rate of 
oxidations is increased less, often only about 2.6 times, and 
the increase is apparently not exactly the same in the eggs of 
different females. We noticed also that after some time the 
rate of oxidation decreases. Could it be possible that the 
cessation of segmentation is due to the fact that the rate of 
oxidation, which at the beginning was rather low, falls below 
the minimum limit, and that this causes the standstill of 
development? This standstill, if prolonged, would lead to 
the loss of the centrosomes (and astrospheres), just as these 
organs are lost in the sea-urchin egg after the maturation 
division. 
This leaves one point still unexplained, namely, the irre- 
versible after-effect of the treatment with the hypertonic solu- 
tion. As we stated in a previous chapter, this after-effect 
may consist in the fact that the treatment with a hypertonic 
solution leads to the formation of a substance which remains in 
