THE EFFECT OF ULTRAVIOLET RADIATION ON THE 

 FERTILIZING POWER OF ARBACIA SPERM. 



MARIE A. HINRICHS, 

 UNIVERSITY OF CHICAGO. 



It is a well established fact that ultraviolet radiation may have 

 an injurious effect on living tissues under certain conditions. 

 That A rbacia sperm is no exception is evident from the diminution 

 of fertilizing power following exposure of sperm to radiation from 

 a quartz mercury-vapor arc whose spectrum range covers 

 approximately 1,850-7,700 A. 



A number of chemical and physical agents have been used to 

 injure the sperm of various animals. In general, such treatment 

 results in a decrease of motility and a lowering of fertilizing 

 power. In eggs which have been fertilized by treated sperm, 

 cleavage is delayed and irregular, gastrulation often impossible, 

 and development abnormal, particularly in the regions of rela- 

 tively high physiological activity. 1 



Sperm may be considered as being endowed with a definite and 

 limited amount of available energy which is expended at a ratio 

 determined by its activity. Cohn, '18, found that the total 

 amount of carbon dioxide produced during the lifetime of sperm 

 was constant; the more active the sperm, the shorter its life. 

 The same investigator (Cohn, '17) found that sperm in acidified 

 water retained their fertilizing power for a long time, although 

 they remained relatively inactive. 



Certain chemical agents are known to stimulate sperm to 

 greater activity, e.g., alkalies, thereby decreasing the length of 

 life of the sperm. (See Gray, '15, and Gee, '16.) Certain 

 investigators have found that eggs give off substances which 

 stimulate sperm to greater activity. Fuchs, '14, found that the 

 blood of freshly caught animals increased the fertilizing power of 

 certain sperm. The same author, in a study of cross-fertilization 



1 For a review of the literature in this connection, see previous paper, Hinrichs, 

 '26b. 



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