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 1s lacking in the wider drone 
cells! 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.? 
Among silkworm breeders the opinion had been repeatedly 
mooted that Bombyx mori could also develop from the unfertilized 
egg, and the observations made on this point by von Siebold 
‘ According to the recent researches of E. Bresslau, the case is still more 
complicated. 
* The assertions of the incorrectness of Dzierzon’s conclusions which have 
recently been vociferously maintained have been proved erroneous. 
