Artificial Parthenogenesis and Heredity 301 



sperm to the eggs the nuclei of the latter had begun to undergo 

 an increase in size in consequence of the previous treatment 

 with fatty acid. In a large number of such eggs Herbst found 

 that the chromatin of the sperm nucleus had undergone a mi- 

 totic division and modification. Herbst considers it likely 

 that this is responsible for the partial elimination of the heredi- 

 tary influence of the sperm. 



It is very interesting that Herbst found plutei which on 

 one side of their bodies were purely maternal while on the other 

 side the paternal influence was noticeable. This he explains 

 on the assumption that the two first cleavage cells received 

 a different amount of paternal chromatin, or, more correctly, 

 different paternal chromosomes. In this way the results of 

 Herbst are in harmony with the modem results concerning 

 the r61e of the chromosome in heredity. 



Tennent has produced results similar to those of Herbst by 

 a different method, namely, by modifying the concentration of 

 HO ions in the sea-water. These experiments, however, have 

 no relation to the problem of artificial parthenogenesis and 

 therefore need not be discussed in this connection. 



