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 shall 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 



