298 Studies In the Phj/Kiolugn of Fertilization 



X. Conclusion. 



Soon Jifter the prefsent work was commenced a pioliminary .•tccount 

 of an investigation by F. R. Lillie published some months previously (2) 

 came to my notice. Before my experiments were completed the full 

 account of this very important work was published (3). It consisted of 

 a study of the reactions of spermatozoa to substances secreted by the 

 eggs, and was thus concerned with the same general problem as the one 

 I was attacking. Lillie's methods, were, however, quite different from 

 mine. The main results were based on observations of the activity of 

 the spermatozoa made both with the naked eye and more especially 

 under the microscope, when the spermatozoa were treated with egg- 

 extracts, substances secreted by the eggs, and chemical agents. Besides 

 this, the effects of the treatments on the subsequent capability of the 

 sperm for fertilizing eggs were tried. Thus, whereas Lillie's results 

 depended mainly on direct observation, mine were based on indirect 

 methods. The effects of the different factors on the spermatozoa were 

 in my case investigated by comparing the subsequent fertilizing powers 

 of the suspensions of sperm experimented upon. The main result of 

 Lillie's work was to show that substances are secreted by the eggs of 

 Arbacia and of Nereis which cause intense activity of the spermatozoa, 

 agglutinate them in masses and to which the spermatozoa are positively 

 chemotactic. 



Now Lillie found evidence for a specificity in the egg-secretion.s. 

 The Nereis "agglutinin" did not agglutinate Arbacia sperm, but the 

 Arbacia substance was agglutinative for Nereis sperm. The Arbacia 

 extract, however, probably contained two agglutinins, one specific for 

 the Arbacia sperm and the other not specific ; for if the substances from 

 Arbacia eggs were kept for some days, Nereis sperm was no longer 

 agglutinated, while Arbacia sperm was. Moreover, the coelomic fiuid 

 of Arbacia contained an agglutinin for Nereis sperm, which did not 

 affect Arbacia sperm. 



It will be remembered that I could find no evidence for specificity 

 in the effects of egg-secretions on the fertilizing power of the sperm. 

 On the contrary, in all the forms tried, the fertilizing power of a sperm- 

 suspension was increased to an exactly equal extent by equal concentra- 

 tions of the egg-secretions of the same and of another form, the two 



