Vol. XXXVI. January, 1919. No. i 



BIOLOGICAL BULLETIN 



THE FERTILIZATION REACTION IN ECHINARACH- 



NIUS PARMA. 



I. CORTICAL RESPONSE OF THE EGG TO INSEMINATION. 



E. E. JUST. 



INTRODUCTION. 



So much has already been written about membrane "forma- 

 tion" in sea urchin eggs that one should perhaps hesitate to add 

 to the list of papers on the subject. The observations here re- 

 ported, however, would seem to fill a gap that has hitherto 

 existed in a critical stage of the fertilization process. We know 

 that the response of the egg to the spermatozoon on insemination 

 first manifests itself in the appearance of a membrane at some 

 distance from the vitellus by some believed to be already on 

 the uninseminated eggs; by others, to be actually formed de 

 novo but accounts as to why and how this membrane forms 

 differ with different workers even where the same egg has been 

 studied. Thus Herbst, Schiicking, Kite and Heilbrunn among 

 others have shown by different methods that the membrane is 

 present on the unfertilized eggs; O. Hertwig originally at least 

 expressed a similar view. R. Hertwig holds this view. On the 

 other hand, Loeb, and the Loeb school generally not only believe 

 that the membrane is formed after insemination but also that its 

 formation is of great significance in the fertilization process; to 

 Robertson, for example, membrane formation is fertilization. 

 Again, we have the notion of Elder and of McClendon that the 

 "fertilization membrane" is a precipitation membrane formed 

 only in the presence of the intact jelly hull of the egg a totally 

 erroneous conception as shown by Harvey ('14). (See also, 

 Lillie, '14.) Finally, while it is usually held that the membrane 

 arises simultaneously from all points of the egg, suggestions have 



