562 FKANK R. LILLIE 



tinating effects, and this result has raised a number of questions, 

 the most important of which relate to the question of specificity, 

 but which could only be defined in the time at my disposal and 

 not definitely answererd. 



The first suggestion that the sperm agglutinating substances of 

 Arbacia and Nereis are different came from the following experi- 

 ment: A raised coverslip preparation of Nereis sperm was made 

 in the usual way and into it were injected a drop each of (1) 

 Arbacia egg-extract in sea-water, (2) drop a of coelomic fluid from 

 a female Arbacia, (3) a drop of coelomic fluid from a male Arbacia. 

 All three caused very extensive firm agglutinations of the Nereis 

 sperm. 



Thus the egg-extract of Arbacia contains an agglutinating sub- 

 stance for the Nereis spermatozoa as well as for its own; but the 

 coelomic fluid of Arbacia also causes agglutination of the Nereis 

 spermatozoa, whereas it is perfectly neutral with respect to its 

 own. This demonstrated, therefore, the existence of at least two 

 sperm-agglutinating substances in Arbacia, namely: One in the 

 egg-extract agglutinative for its own sperm and that of Nereis, 

 and one in the coelomic fluid not agglutinative for its own sperm, 

 but agglutinative for the foreign sperm of Nereis. The prob- 

 ability is, therefore, that the egg-extract contains both substances 

 seeing that it is agglutinative for both kinds of spermatozoa. 

 This was afterwards demonstrated. 



The reciprocal experiment proved the difference of the Nereis 

 and Arbacia agglutinating substances conclusively, for it was 

 shown that Nereis egg-extracts strongly agglutinative for sperm 

 of Nereis had no agglutinating effect on Arbacia sperm within the 

 limits of attainable concentrations (several experiments). The 

 Arbacia fluids are extremely toxic apparently to the Nereis sperm 

 for the agglutinations were more solid than those caused by the 

 iso-agglutinating substance. The absence of a reciprocal effect, 

 that is, of Nereis extracts on Arbacia sperm, is therefore all the 

 more striking. 



The same difference may be shown by the reactions of sperm 

 suspensions of both species to one another. The experiment was 

 made in the following manner: 



