THE GENETICS OF HABROBRACON JUGLANDIS ASHMEAD 



duced from unfertilized eggs, and females from 

 fertilized eggs. 



Nachtsheim in 1913 had shown that somatic 

 cells of the honey bee possess the haploid num- 

 ber of chromosomes in the case of the male, and 

 the diploid number in the case of the female. 

 Sex determination in the Hymenoptera was then 

 assumed to rest upon the possession of one sex 

 chromosome in the haploid male or two in the 

 diploid female. 



Bridges (1925), discussing sex determination 

 in the bees and wasps stated that it was the 

 outstanding unsolved puzzle, although before 

 the genie balance theory it seemed one of the 

 clearest and simplest of cases. 



The explanation of sex determination in Hab- 

 robracon was further complicated when diploid 

 males were found to occur occasionally. Tests 

 made with the first mutant type, the recessive 

 orange eye-color, demonstrated that three types 

 of individuals, haploid males from unfertilized 

 eggs and diploid males and females from fertil- 

 ized eggs, occur regularly in the species when 

 parents are related. When orange females were 

 crossed with the wild-type black-eyed males, 

 there appeared not only the expected black-eyed 

 heterozye;ous females from fertilized eggs and 

 orange haploid males from unfertilized eggs, 

 but also a smaller group of "anomalous" sterile 

 or almost sterile males which were black-eyed. 

 Since males were then regarded as necessarily 

 haploid, these "patroclinous" sons were thought 

 to be either androgenetic or mosaic in origin, 

 having arisen through failure of syngamy (P. W. 

 Whiting, 1921a). 



This view persisted until 1925 when it was 



92 



