ULTRAVIOLET RADIATION AND THE FERTILIZA- 

 TION REACTION IN ARBACIA PUNCTULATA. 



MARIE A. HINRICHS, 

 DEPARTMENT OF PHYSIOLOGY, THE UNIVERSITY OF CHICAGO. 



For a general consideration of the fertilization problem, the 

 reader is referred to Chapter VIII., " Fertilization," by F. R. 

 Lillie and E. E. Just, in Cowdry's "General Cytology," 1924; 

 also to " Problems of Fertilization," by F. R. Lillie, 1919. In 

 this paper, the studies of individual authors will be cited only 

 where it seems desirable to refer to results which have a particular 

 bearing on those obtained in the experiments about to be de- 

 scribed. 



The fertilization reaction may be modified by the direct action 

 of a physical or chemical agent upon either or both of the sex 

 components, or upon the zygote. Such interference results in the 

 production of differentially modified larvae, of irregular cleavage 

 (often incomplete), of lack of membrane formation, or even of 

 cytolysis. The magnitude of the injury is a function of the dos- 

 age and the time at which the exposure is made. This is easily 

 demonstrable with Arbacia and ultraviolet radiation (Hinrichs, 

 '26,0,20. 



Furthermore, it is possible by means of radiation to interfere 

 with the characteristic behavior of the sex cells, e.g., the motility 

 of the sperm is lost (Lillie and Baskervill, '22, and Hinrichs, 

 '26c), and the agglutinability by normal egg-water is reduced or 

 lost. The permeability of both sex components is altered, and the 

 fertilizin-producing capacity of the egg is lost, following radiation. 



Methods. In the experiments involving the radiation of eggs, 

 sperm, or egg- water, the material was placed in open dishes (im- 

 mersed in a water bath) at a distance of 12.5 cm. from the lamp. 

 (A few exposures were made at 23.0 cm. from the lamp, for 

 comparison.) The radiation source was a Cooper-Hewitt quartz 

 mercury-vapor lamp, operating at no volts D.C. and about 4 

 amperes. 



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