STUDIES OF FERTILIZATION 573 



Loligo to CO2 (see p. 528) indicates still greater differences in 

 characteristic behavior. And it may be that the differences of 

 chemotactic behavior of the spermatozoa of various animal 

 phyla will turn out on investigation to be extensive. I am very 

 far, therefore, from wishing to generalize any of the principles 

 that we have found to hold true for Nereis and Arbacia. Sound 

 generalizations must be based on much more extensive work. I 

 have made some observations on the sperm of Platynereis mega- 

 lops which demonstrate great differences as compared with Nereis 

 in spite of the close relationship, correlated, no doubt, with dif- 

 ferences in breeding behavior. While the common form of organ- 

 ization of flagellated spermatozoa points to fundamental principles 

 of behavior in common, yet it must not be forgotten that each 

 kind of spermatozoa has the chemical composition of the species, 

 and may therefore have entirely specific forms of behavior. 



The agglutination of the spermatozoa by normally formed 

 egg-exudates of the same species indicates the possibility of study- 

 ing the chemistry of fertilization directly through use of the 

 spermatozoa as indicators. The very few and incomplete results 

 which I was able to obtain in the time at my disposal seem to me 

 to indicate a fruitful line of work. It would be interesting, for 

 instance, to investigate whether or not the ova of hermaphrodite 

 animals produce a sperm auto-agglutinin, that is, an agglutinat- 

 ing substance for spermatozoa of the same individual. Morgan's 

 work on Ciona has shown that the failure to self-fertilize is in this 

 case due to failure of penetration of the spermatozoon. It is 

 difficult, as he points out, to explain this on any mechanical 

 grounds. But if a specific agglutination is a necessary step in 

 union of ovum and spermatozoon, the failure to produce an auto- 

 agglutinin would explain the failure of self-fertilization. ,We 

 would have in this event a precise parallel to the usual failure to 

 produce blood auto-agglutinating substances in experiments on 

 immunity, though iso-agglutinins are readily produced. 



Godlewsky ('11) has shown that there is an antagonism between 

 the sperm of certain animals (Chaetopterus and Echinids) which 

 destroys the fertilizing power of each when mixed together for a 

 certain length of time. He compares this to the antagonistic 



