Life-cycle of Some Hymenopterous Insects 355 



opportunity is left to deposit new eggs in the cells, if the workers 

 remove them. 



In recent years an apiarist, Dickel of Darmstadt, has claimed 

 to have discovered facts that contradict the Dzierzon theory, and 

 his contention, although it appears ill-founded, has led to a re- 

 examination of the theory. He has tried to show that drone eggs 

 as well as queen and worker eggs are fertilized, and that the 

 sex is determined by the treatment to which the eggs are sub- 

 jected by the workers. He admits that males may come from 

 unfertilized eggs of queens and of workers, but he calls these 

 false drones that are incapable of procreation. He believes that 

 before fertilization the egg contains only the male elements. 

 The sperm cell contains only female elements. After union 

 these sexual elements are equally balanced, and the fate of the 

 embryo is determined by the following external factors. In 

 making the brood cells the wax is kneaded in the mouths of the 

 workers, and impregnated with the saliva. The kind of saliva 

 used is different for the drone and for the worker cells, and its 

 presence in the walls of these cells determines the kind of secre- 

 tion that is poured over the egg by the workers when it is laid. 

 This secretion determines the sex of the egg. One kind of 

 saliva is used for the queen larva, and causes a fertile female to 

 develop ; another kind causes the male to develop. If both of 

 these are put into the same cell, they retard the development of 

 the sexual organs and a worker is produced. There is also an- 

 other nourishing secretion that is used for all kinds of larvae, 

 and does not affect the sex. Dickel tried to show by transferring 

 drone eggs to worker cells, and vice versa, that the sex of the 

 young larva can be changed by the change in food that the bees 

 give to it in a foreign cell. The experiment is open to the criti- 

 cism mentioned above, namely, that the workers may remove the 

 egg, although the possibility might be very simply tested by 

 removing the queen. 



This ingenious and highly speculative, not to say fanciful, 

 idea of Dickel has so little in its favor in the way of scientific 

 evidence, and so much opposed to it that seems fairly well 



