70 



THE AMERICAN NATURALIST [Vol. XLTI 



from three males of the same locality (indicated by 1-, l\ in 

 the table), and the other three were fertilized by sperm of 

 three males from another locality (Schleissheim, =S in dia- 

 gram). The converse experiment was also carried out. The 

 results are given in the next table, in which the double sign 

 ? £ indicates that the sexual organs were in an indifferent con- 

 dition. It will be observed that a very large number of indi- 



those cultures that developed best there was a decided excess of 



different forms and no males. > ' 



80<? : 77$^ 



<?, 59^ : 65ft?, 11$ 



Ilertwig thinks that the results show that the sperm has a dis- 

 tinct influence on sex-determination. He suggests that in the 



so that a slight influence on the part of the male sufficed to turn 

 the scales. He adds that it is thinkable that as a rule the eggs 



determined that the relatively small influence of the male has 

 no influence. It will be noted, however, that in Ilertwig 's own 

 experiment the condition of the two females selected was very 

 different, yet there is a surprising similarity in the results pro- 

 duced when the males .that fertilized the eggs are considered. 



Tlie experimental results are not sufficient to give any posi- 

 tive light on the question, but the method that Hertwig has 

 employed in the last experiment is one that promises to give 

 an answer to the question whether the egg or the sperm deter- 



"Tf 6 one 6 may hazard a° guess, the results of Ilertwig 's experi- 



nat'ion. Since normally all the eggs are fertilized it can not be 



J^S^ratingly injured or killed by the cold of winter. In 

 regard to the sperm, however, it is possible that more of one kind. 



