OTHER METHODS OF SEX-DETERMINATION 237 



tion in bees. When the maturation of the germ-cells in the 

 male takes place, the first division is abortive. A small 

 cell is pinched off without chromosomes (Fig. 86). At the 

 second division the chromosomes divide. Half pass into 

 one cell, that is very small and later degenerates; half 

 remain in the larger cell, that becomes the functional 

 spermatozoon and contains the haploid number of chro- 

 mosomes. This number it brings into the egg, which, as 

 stated, then develops into a female. 



There are a few cases on record (Newell) where two 

 races of bees have been crossed and the progeny of the 

 hybrid recorded. The males are said to show the charac- 

 ters of one or the other original race. This is expected, in 

 so far as the two races differ in genes in one and the same 

 pair of chromosomes, because these would be separated 

 at reduction, and one or the other would be retained in 

 the haploid egg that produces a male. But if the racial 

 differences depend on genes lying in different pairs of 

 chromosomes, no such sharp distinction into two classes 

 of grandsons is to be expected. 



The worker bees (and ants) occasionally lay eggs. 

 These become males, as a rule, which is expected, since 

 the workers cannot be inseminated by the drones. There 

 are records in ants of the rare appearance of sexual fe- 

 males from workers' eggs. It may be supposed that this 

 is due to the retention of a double set of chromosomes. In 

 the ''Cape bees" the production of females (queens) 

 from workers' eggs is said to be a common occurrence. 

 Provisionally we may apply the same explanation as that 

 given above for the females of worker ants that rarely 

 produce eggs some of which, under special conditions, 

 develop into females. 



The direct transmission of the characters of the mother 

 to her haploid sons has been more completely demon- 

 strated in Whitings' work on the parasitic wasp, Habro- 



