HAPLOIDS 145 



from which it was derived. The first maturation of the 

 pollen mother cells of these haplonts was irregular, few 

 or many of the chromosomes passing to the poles, the rest 

 remaining at the equator of the spindle. The second matu- 

 ration division was somewhat more regular, but lagging 

 chromosomes failed to reach either pole. 



Nature seems to have been successful in producing a 

 few haplonts in species in which one sex is diploid. Male 

 bees, wasps, and ants are haplonts. The eggs of the queen 

 bee contain 16 chromosomes, which become 8 bivalents 

 after conjugation (Fig. 85). Two maturation divisions 

 take place, reducing the number to 8 chromosomes. If 

 an egg is fertilized it produces a female (queen or 

 worker) with the diploid number of chromosomes, but if 

 an egg is not fertilized it develops parthenogenetically 

 with the half number of chromosomes. 



An examination of the nuclear and cell-size of the dif- 

 ferent tissues of the female and male bees (Boveri, Meh- 

 ling, Nachtsheim) has shown that, in general, there is no 

 constant difference between the diplont and the hap- 

 lont. There is, however, a peculiar condition in the early 

 embryonic stages both of the female and male bee that 

 has somewhat complicated the situation. In the cells of 

 the embryo of the female, the chromosomes become twice 

 as numerous as at first, apparently by each chromosome 

 separating into two parts. In the cells of the embryo of 

 the male, the same process occurs, and is there repeated 

 even a second time, so that there appear to be 32 chromo- 

 somes present. The evidence seems to indicate that the 

 chromosomes do not actually increase in number but 

 ''fragment." If this is the correct interpretation there is 

 no increase in the number of the genes. The female has 

 still twice tlie number of those in the male. What relation, 

 if any, this fragmentation may have to nuclear size is not 

 clear at present. 



