SEX DETERMINATION / 



52.57 



stitution of gametes, and which, in some cases at least, are 

 capable of actually functioning as gametes. It would seem 

 that in such cases the female must have a duplex chromosome 

 composition, since two gametes have united to pnxhice it, 

 whereas the male can be only simplex, since he represents 

 a developed gamete. 



The case of the honeybee affords a familiar example, l^ie 

 mother bee, or "queen "of the hive, lays eggs which are 

 capable of development either vnth or without fertiHzatioii. 

 The mother is able to produce or to withhold fertlHzalion 

 according to circumstances, for she has in a sac connected 

 with the oviduct a supply of sperm received at mating. The 

 eggs pass the outlet of this sac as they are laid. The outlet 

 of the sac is controlled by muscles which relax when an egg 

 is to be fertilized, permitting sperm to come in contact with 

 the egg, but closing the outlet tightly when the egg is not to 

 be fertilized. Fertilized eggs are laid in cells of the reguhir 

 size in the wax comb, but unfertilized eggs are laid only in 

 cells of a larger size known as drone cells. The fertilized eggs 

 develop into females, even if they are moved from ordinary 

 cells to drone cells; but the unfertilized eggs produce males, 

 even if they are transferred to cells of ordinary size, in which 

 case, however, they will become small-sized drones because 

 of the limited amount of space in which they complete their 

 growth. Fertilized eggs developing in cells of ordinary lioney- 

 comb size produce female bees with imperfectly-developed 

 sex organs, known as workers. They are the individuals that 

 gather honey and pollen and feed the young of the colony. 

 A fertilized egg, which produces a larva that receives special 

 care and nourishment and develops in a cell of unusual size, 

 gives rise to a queen, a fully developed female cai)al)le of mat- 

 ing and laying great numbers of eggs, but without the struc- 

 tural peculiarities or instincts of workers. From these facts 

 it will be clear that, in the bee, fertilization detennines sex, 

 though environment (size of cell, food of the lars^a) may de- 

 termine many other characteristics of the individual. As 

 regards their origin, the female is a zygote produced by the 



