548 FRANK R. LILLIE 



it will be recalled that N/2000 gives a distinct reaction. Posi- 

 tive reactions were not secured with N/1000 HCl or HNO3, 

 but were with N/250. The ring formed in response to N/250 

 H0SO4 grows somewhat owing to diffusion of the acid; in the case 

 of N/50 and N/10 H2SO4 the growth is much greater, in general 

 in proportion to concentrations. 



As in Nereis alkalis agglutinate, but cause no aggregation. 

 KOH was tested in two ways: (1) addition of a small quantity of 

 N/2000 KOH in sea-water to a vial of fresh sperm suspension 

 caused macroscopic agglutinations which are irreversible. (2) a 

 drop of N/2000 KOH injected into a suspension beneath a raised 

 cover fills in a short time with sperms that agglutinate ; but there 

 is no chemotaxis, and in a short while the drop is left to one side 

 by aggregation of the sperm away from it, owing to rise of CO2 

 tension elsewhere. 



Reaction to egg-secretions 



As contrasted with the slowness of reaction of Arbacia sperma- 

 tozoa to acids, the reaction to egg-secretions is instantaneous 

 and clear cut. There is a most pronounced positive chemo- 

 taxis, as tested with drops even of very weak egg-extract injected 

 into a sperm suspension mounted beneath a raised cover-shp; 

 but this is always associated with agglutination, and is, therefore, 

 best considered under that head. 



IV. AGGLUTINATION PHENOMENA AND REACTIONS OF 

 SPERMATOZOA TO EGG-SECRETIONS 



1. INTRODUCTION 



Following the demonstration of definite chemotactic behavior 

 of spermatozoa of Nereis and Arbacia the question naturally 

 arises what relation, if any, has this form of behavior to the union 

 of egg and spermatozoon in fertilization. As is well known, the 

 mere observation of the interaction of the sexual elements in 

 fertilization led long ago to the theory that the egg attracts the 

 spermatozoon to itself by chemotaxis, and fusion results from 

 active penetration of the ovum by the spermatozoon. But in 

 recent years there has been a tendency to deny both of these 



