90 OTTO GLASER. 



TABLE V. 



INDIVIDUAL EGGS BEFORE AND AFTER FERTILIZATION. 



With the exception of the starred eggs, D% 3, and E 2, which 

 within the limits of error may easily be considered constant, all 

 the eggs showed a noticeable decrease. 



The fact brought out by these measurements constitutes an 

 additional support for the conception that an 'increase in the 

 permeability of the egg accompanies fertilization. With such 

 increase, other conditions remaining constant, one would expect 

 a change in volume. The fact that unfertilized eggs, under 

 certain conditions, may remain unaltered for hours, whereas 

 there is a noticeable decrease in their diameters immediately 

 after fertilization, strongly emphasizes the change that takes 

 place. 



COMPARISON OF UNFERTILIZED AND FERTILIZED OVA OF Asterias. 



The results obtained in the case of Arbacia are more strikingly 

 illustrated by a control observation made on the ova of Asterias 

 forbesii. The measurements were made on eggs which had been 

 removed from the ovaries and allowed to stand one hour in sea 

 water in order to complete maturation. Tracings were made of 

 two small groups from two females and these groups were then 

 inseminated. It is impossible to identify individual eggs in 

 this case, but this does not invalidate the result, since no eggs 

 were either added or removed upon the addition of the sperm. 

 Seventeen eggs derived from one female, and eight from the other 



