GERM CELLS IN THE ARTHROPODA 143 



grate, so they probably take part in development 

 after becoming associated with some other part of 

 the egg. If these nuclei were qualitatively different 

 they should produce germ cells and other varieties of 

 cells in whatever region they chance to reach. It 

 is evident that they are not potentially different 

 and that their "prospective potency" and "pro- 

 spective significance" do not coincide. The cyto- 

 plasm is, therefore, the controlling factor at this 

 stage in the germ-cell cycle, although cytoplasmic 

 differentiations are for the most part invisible and 

 probably the result of nuclear activity during earlier 

 stages. 



Hymenoptera. a number of papers have ap- 

 peared which contain references to the germ glands 

 of Hymenoptera (Hegner, 1909, pp. 245-248). 

 The most important of these from the standpoint of 

 the present discussion are: (1) Silvestri (1906, 1908) 

 and Hegner (19146) on some parasitic species, and 

 (2) Petrunkewitsch (1901, 1903), Nachtsheim (1913), 

 and others on the honey-bee. 



In an endeavor to test the " Dzierzon theory," 

 that the eggs which produce drone bees are normally 

 unfertilized, Petrunkewitsch (1901-1903) discovered 

 some usual maturation divisions. In "drone eggs" 

 the first polar body passes through an equatorial 

 division, each of its daughter nuclei containing one- 

 half of the somatic number of chromosomes. The 

 inner one of these daughter nuclei fuses with the 

 second polar body, which also contains one-half of 

 the somatic number of chromosomes ; the resultant 



