482 



MARIE A. HINRICHS. 



The effect of ultraviolet radiation on fertilizing power is, in 

 general, roughly proportional to the dosage, e.g., exposures of 5 

 minutes are more effective in causing immediate reduction of 

 fertilizing power than are exposures of a minute or less. Also, 



IOOt 



FIG. 3. The effect of length of period of exposure on fertilizing power. The 

 degree of reduction is roughly proportional to the dosage of radiation, a-f represent 

 the lengths of the periods of exposure in minutes, a o, b j, c , d i, e 3, 

 / 10. Ordinates represent the percentage of eggs cleaved. Abscissae represent 

 the dilutions of sperm, e.g., 8 J 8 %. etc. 



