476 



MARIE A. HIXRICHS. 



TABLE I. 



THE EFFECT OF RADIATION ON THE FERTILIZING POWER OF SPERM. 1 



branes, in comparable lots of eggs fertilized by exposed sperm, 

 as compared with eggs fertilized by normal sperm. Also, the 

 rate at which fertilizing power is lost is greater in the more 

 dilute suspensions. (See Fig. i.) Bohn and Drzewina, '23, 

 showed that the more dilute the sperm suspensions of Arbacia 

 were, the more susceptible they were to the inhibiting influence 

 of neutral red in the presence of light. 



Figure i indicates that in general, radiation shifts the curve 

 of the dilution effect to the left along the time axis. The greater 

 the dilution, the more immediately is the rate of falling off 

 augmented as compared with normal lots. For example, Fig. i 

 gives the following data with respect to increase in the rate of 

 falling off in the fertilizing power of Arbacia sperm. In dilution 

 5 8 per cent. (Curve A], the increase in rate is not felt until one 

 hour after exposure, but the continued decrease in fertilizing 

 power lasts until three hours after exposure. In more dilute 



1 Measured by the percentage of cleavage in normal eggs fertilized by treated 

 sperm. 



Figures 8-16 represent sperm dilutions of Y^-V^%. (n and 12 are averages 

 of three experiments; 15 of two; and the rest, one each.) 



Figures in the first column to the left represent the time in minutes following 

 initial dilution and exposure to radiation. 



