258 LEIGH HOADLEY. 



II. The Normal Fertilization Reaction in 

 Arbacia Punctulata. 



In order to understand the later discussion, it will be wise 

 here to summarize the phenomena of the normal fertilization 

 reaction in Arbacia. These were described in great detail by 

 Lillie ('14), though some of the events had been incompletely 

 described by von Dungern ('02). Fol ('79) described the pene- 

 tration of the spermatozoon and the elevation of the fertilization 

 membrane in a classical monograph. 



Before the spermatozoon comes into contact with the egg 

 itself it is activated and directed toward the egg as described by 

 Lillie ('13). The egg, from the time of rupture of the germinal 

 vesicle up to the time of fertilization, or, when fertilization is 

 barred, up to the time of cytolysis, produces an iso-agglutinin 

 (Lillie '13) or fertilizin (Lillie '14) which produces a reversible 

 agglutination of the spermatozoa to the egg. Between the time 

 of the agglutination of the spermatozoa to the egg and the 

 beginning of the fertilization reaction, there is a latent period 

 which is very short but variable in Arbacia. This is followed by 

 a very rapid initial reaction which produces a sterilization of the 

 egg against other spermatozoa, described by Just ('19) as "a 

 wave of negativity." The penetration of the spermotozoon 

 occurs immediately, followed by the elevation of the membrane. 

 In a given lot of fresh eggs, the time elapsing before membrane 

 elevation is very variable. At 19. 5 C. some eggs appear with 

 membranes fully formed in from 15 to 30 seconds while others 

 require much longer. Elevation of the membrane is too rapid 

 for observation in Arbacia and it seems probable that the variable 

 is due to the latent period. With stale gametes the process may 

 extend over five minutes or more and is often accompanied 

 by polyspermy. 



III. Methods. 



The experiments described in the following pages are very 

 simple. Eggs were removed from good ripe females by making 

 a circumferential cut around the animal and removing the 

 gonads intact to about 150 c.c. of sea water in a finger bowl. 

 The ovaries were then cut a number of times and the ova allowed 



