258 PARTHENOGENESIS VII 



females) , number of the same, number of cells observed 

 when the experimental conditions were established, 

 date and duration of the experiment, maximum number 

 of female workers employed in the affairs of the nest, 

 number of larvae, pupae, and wasps of the partheno- 

 genetic brood found at the conclusion of the experi- 

 ment. After the account of the artificially obtained 

 results, two cases are recorded in which Siebold found 

 a parthenogenetic colony naturally established by an 

 accident which had destroyed their queen and comb. 



Before concluding this chapter of his book, Siebold 

 makes the very important observation that the facts 

 observed in the parthenogenesis of Polistes are in 

 opposition to the view maintained by Ley dig, viz. 

 that the sexual difi"erentiation of the egg is independent 

 of its fertilisation, and that the evolution of the male 

 sex is due to diminution of nutrition and warmth. 

 Bessels has already, in opposition to Landois, shown 

 that this is not the case in the bee. If it were true 

 for Polistes, the eggs laid in the early year, when it 

 is cold, and when there is only the queen to attend 

 to the larvae, should produce drones. On the contrary, 

 they produce females, and the drones appear precisely 

 at the time when warmth and nourishment are most 

 abundant. 



Siebold concludes, therefore, that (l) the eggs 

 bring with them from the ovary the capacity of 

 difi'erentiating themselves as males, and (2) of de- 

 veloping themselves, independently of male influence 

 into male individuals ; (3) but the same eggs can be 

 changed in these properties by the influence of the 



