AUTHOR'S ABSTRACT OF THIS PAPER ISSUED 

 BY THE BIBLIOGRAPHIC SERVICE, FEBRUARY J 



STUDIES OF FERTILIZATION. 



IX. ON THE QUESTION OF SUPERPOSITION OF FERTILIZATION ON 

 PARTHENOGENESIS IN STRONGYLOCENTROTUS PURPURATUS. 



FRANK R. LILLIE, 

 UNIVERSITY OF CHICAGO. 



The statement of Loeb (1913, p. 234; 1915, p. 260-261) that 

 eggs of Strongylocentrotus purpuratus which have formed mem- 

 branes as a result of butyric acid treatment can be fertilized with 

 sperm if the membranes are destroyed by shaking raises a diffi- 

 cult question in the problem of fertilization. It is known that 

 eggs in which membranes have been formed by spermatozoa are 

 incapable of refertilization, even if the membranes are destroyed 

 by shaking immediately after their formation. We have every 

 reason to believe that the membrane-forming reaction by butyric 

 acid is the same as by fertilization. The after effects should 

 therefore be the same. 



In an examination of this problem in the case of Arbacia, C. R. 

 Moore (1916) showed that this is the case, viz: that, given a 

 full membrane reaction by butyric acid, the eggs became in- 

 capable of fertilization, even if the membranes are removed. It 

 is, however, possible to superimpose fertilization on an incom- 

 plete reaction caused by butyric acid to a variable extent which 

 is roughly proportional to the degree of the original reaction. 

 Just (1919) investigated the same problem in the case of 

 Echinarachnlus parva, and determined that eggs which have 

 formed full membranes after butyric acid treatment do not re- 

 spond to subsequent insemination whether the membranes are 

 removed or not. 



The writer took advantage of the opportunity afforded by a 

 stay at the Hopkins Marine Station in Pacific Grove, California, 

 in January and February, 1920, to repeat Loeb's experiments on 

 the same species that he used. The results obtained diverged 



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