138 JACQUES LOEB 



some time in sea \yater.^ The writer fails to. see any reason for 

 assuming that the cell division in Glaser's experiments was induced 

 by 'fertilizing The fact that the composition of the mixture 

 which he used was unknown is not sufficient proof that ' f ertilizin ' 

 was the active agency. 



In conclusion, the writer would like to call attention to the fact 

 that the cluster formation described in this paper or the agglutina- 

 tion of sperm described by Lillie inhibit the fertilizing effect of 

 the spermatozoa instead of enhancing it, since the cluster forma- 

 tion prevents the spermatozoa from reaching the egg. Even from 

 a teleological viewpoint it is difficult to understand why a sub- 

 stance which only prevents the fertilizing action of the sperm 

 should be a necessary link in such action. The wTiter is inclined 

 to believe that the cluster formation or agglutination of sperm does 

 not occur when fertilization takes place under natural conditions. 



The writer is not quite sure whether his interpretation of the 

 cluster formation of the spermatozoa as a tropistic reaction will 

 have to be modified or not. If it should turn out to be essentially 

 or partly correct, it might be worth while to point out that we have 

 many examples of tropistic reactions which are of no possible use 

 to the species, e.g., all the phenomena of galvanotropism which are 

 only laboratory products. 



The writer takes pleasure in expressing his thanks to Prof. 

 S. S. Maxwell of the University of California for his kindness in 

 putting the Herzstein Laboratory at New Monterey at the 

 writer's disposal. 



SUMMARY 



1 . The writer describes the formation of clusters of spermatozoa 

 which is observed when the sperm of a sea urchin is put into the 

 supernatant sea water of eggs of the same species. This specific 

 phenomenon of clus^ter formation may possibly be identical with 

 the specific phenomenon described under the name of sperm agglu- 

 tination in recent publications of F. Lillie. 



« Arch. f. Entwcklngsmechn. d. Organ., Bd. 36, p. 626, 1913. 



