THE FERTILIZATION-REACTION IN ECHINA- 

 RACHNIUS PARMA. VII. 



The Inhibitory Action of Blood. 



E. E. JUST,i 

 Rosenwald Fellow in Biology, National Research Council. 



The present communication aims to set forth results of experi- 

 ments made during two seasons (19 19 and 1920) at the Marine 

 Biological Laboratory, Woods Hole, Mass., to test that part of 

 Lillie's fertilizin theory which postulates that blood (in Arbacia) . 

 inhibits fertilization through intervention of the fertilizin and the 

 egg (Lillie, '14). The present writer was firmly of the opinion 

 that this postulated action might be merely a surface effect: that 

 despite the agglutination of Arbacia sperm, by Arbacia egg-water 

 in the presence of specific blood, the main action of the blood is 

 on the surface of the egg so that sperm can not enter. The results 

 of the experiments here reported, however, show that, in the egg 

 of Echinarachnius parma at least, this is not the case : blood blocks 

 fertilization in this egg by interfering with the reaction of fertilizin 

 and egg and not with the sperm and fertilizin at the surface of the 

 egg. For repeated observations reveal that both in straight and 

 cross fertilization, with Arbacia sperm, eggs of Echinarachnius 

 inseminated in blood, though they fail to develop, nevertheless take 

 in sperm. We may divide the experiments into two groups : those 

 that deal with straight fertilization and those that deal with cross 

 fertilization with Arbacia sperm. 



I. 



Eggs of Echinarachnius obtained by cutting up ovaries in sea- 

 water invariably give low fertilization percentages. Thus the early 

 observations — 1910, 1914, 191 5 — made on such eggs gave the im- 

 pression that this is a poor egg for the study of fertilization. An 

 egg suspension strained from ovaries cut up in sea-water shows a 

 slight turbidity or greater depth in color depending upon the 

 amount of blood and detritus present. My notes indicate that 

 fertilizing power falls off with increasing depth of color. With 

 shed eggs, on the other hand, the case is quite different: they in- 

 variably yield 100 per cent, fertilization. If, however, shed eggs 



1 Zoological Laboratory, Howard University. 



10 



