428 ROBERT W. HEGNER 



Conclusion. From the evidence at present available we must 

 conclude that amitotic division of the germ cells has not been 

 demonstrated, and that not until such a process is actually 

 observed in living cells will any other conclusion be possible. 



4. HYMENOPTERA 



A number of papers have appeared which contain references 

 to the germ glands of Hymenoptera (Hegner, '09a, pp. 245-248). 

 The most important of these from the standpoint of the present 

 discussion are (1) Silvestri ('06, '08) on some parasitic species, 

 and (2) Petrunkewitsch ('01, '03), Dickel ('04), and Nachtsheim 

 ('13) on the honey-bee. 



In an endeavor to test the 'Dzierzon theory,' that the eggs 

 which produce drone bees are normally unfertilized, Petrunke- 

 witsch ('01-'03) discovered some unusual 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 daugh- 

 ter nuclei fuses with the second polar body, which also contains 

 one-half of the somatic number of chromosomes; the resultant 

 nucleus with sixteen chromosomes, the 'Richtungscopulations- 

 kern', passes through three divisions giving rise to eight 'doppel- 

 kernige Zellen.' After the blastoderm is completed, the prod- 

 ucts of these eight cells lie in the middle line, near the dorsal 

 surface of the egg, where the formation of the amnion begins; 

 the nuclei of these cells are small, and lie imbedded in dark 

 staining cytoplasm. Later they are found just* beneath the 

 dorsal surface near the point of union of the amnion with the 

 head-fold of the embryonic rudiment. They are next located 

 between the epithelium of the mid-gut and the ectoderm; 

 from here they migrate into the coelomic cavities, and finally, 

 at the time of hatching, form a 'wellenartigen' strand, the germ- 

 gland, extending through the third, fourth, fifth and sixth ab- 

 dominal segments. The fertilized eggs of the bee were also 

 examined by Petrunkewitsch, but no 'Richtungscopulationskern' 

 was discovered. In these eggs ''entstehen die Genitaldriisen 



