35^ Experimental Zoology 



established, that it need scarcely be discussed seriously. Pe- 

 trunkewitsch has severely criticised Dickel's views, and has 

 pointed out that the supposed experimental proofs are all open 

 to question ; • that his ideas in regard to fertilization are hazy ; 

 and that a renewed investigation by means of the more perfect 

 modern technique has confirmed v. Siebold's and Leuckart's 

 statements that spermatozoa are not present in. drone eggs. 

 For instance, Petrunkewitsch found the sperm nucleus in 23 out 

 of 29 eggs from worker cells. On the other hand, of 94 eggs 

 from drone cells not one contained a spermatozoon. These 

 eggs were in the stage when the first polar body was present. 

 In the following cases the second polar body was forming: — 

 62 eggs from worker cells all contained sperm asters, while 272 

 from drone cells contained no asters, except in one case. It may 

 be that in this one case the queen had erred and placed a fer- 

 tilized egg in a drone-cell, which is supposed to occasionally 

 occur. These results furnish a further confirmation of Dzier- 

 zon's theory. 



Other Hymenoptera 



The ants are closely related to the bees and show apparently 

 similar conditions in regard to the determination of sex. It has 

 long been claimed that the unfertilized eggs of the queen and 

 the unfertiHzed eggs of the workers produce males. Hence 

 Dierzon's theory has been extended to this group also. 



In the last few years, however, some cases have been recorded 

 that seem to show that workers may appear in nests that have 

 no queen, and which, therefore, have come from workers' eggs, 

 which are never, as far as known, fertilized. The seminal recep- 

 tacle is absent in the workers, hence there would be no oppor- 

 tunity for the storage of sperm, and since in one case workers 

 appeared during three years, they must have come from par- 

 thenogenetic eggs. 



Wheeler has recently brought together the best authenticated 

 cases of this kind. Tanner records for Atta cepholotes that a 

 group of worker ants in an artificial colony produced eggs most 



