44 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 



conclusion that male bees the drones arise from unfertilized 

 eggs, workers and queens, on the other hand, from fertilized 

 eggs. He discovered that the queen copulates only once in 

 her life, and that this never takes place in the hive, but in the 

 air, during the so-called nuptial flight. After pairing, the 

 sperm remains in a vesicle, the female's receptaculum, the duct 

 of which is passed by the egg. If, now, the queen is laying 

 an egg in a worker cell, a trace of sperm is pressed out of the 

 receptaculum when the egg passes the opening of its duct, and 

 so the egg is fertilized. But when the queen lays an egg in 

 the larger drone cell, the egg passes the duct without any 

 sperm being pressed out. Von Siebold represented that bees 

 behave consciously; but it is more likely that a purely physio- 

 logical explanation may be found. It is, e.g., possible that in 

 the narrower worker cells the muscles which empty the recep- 

 taculum are reflexly or mechanically set in activity, while 

 the mechanical stimulus thereto is lacking in the wider drone 

 cells. 1 Dzierzon was able to bring to the support of this view 

 a series of observations; thus, for example, queens which 

 have been prevented from taking the nuptial flight by defective 

 wing development invariably give rise to drones; the same is 

 the case in old queens which continue to lay eggs when their 

 receptaculum contains no more sperm; and workers, which 

 cannot copulate owing to the rudimentary development of 

 their sexual organs, occasionally lay eggs from which without 

 exception males are hatched. 



Dzierzon's views and observations were confirmed and 

 completed by the investigations of von Siebold, Leuckart, and 

 von Berlepsch. 2 



Among silkworm breeders the opinion had been repeatedly 

 mooted that Boinbyx mori could also develop from the unfertilized 

 egg, and the observations made on this point by von Siebold 



1 According to the recent researches of E. Bresslau, the case is still more 

 complicated. 



2 The assertions of the incorrectness of Dzierzon's conclusions which have 

 recently been vociferously maintained have been proved erroneous. 



