20 THE ORIGIN OF GYNANDROMORPHS. 



chromosomes that also carries the factors for the secondary sexual char- 

 acter A. The primary sex character of the female is represented by F, 

 carried by a second pair of chromosomes, and the secondary sexual 

 character by G, both as before, carried in the same chromosome. In 

 other words, the two pairs of sex chromosomes are (FG) (FG) and (MA) 

 (MA) for the female, and, for the male, (FG) (fg) and (MA) (MA). 



Lang suggests that a loss by mutation takes place in females (as 

 above) in the sense that one FG disappears and may now be repre- 

 sented by (fg). The resulting division is shown in text-figure 5. The 

 mutation causes the sex-balance in the cell on the right side to turn 

 into a male, while that of the left remains a female. Lang appears to 

 mean that the "mutation by loss " is the loss of a daughter chromosome. 



If we ignore the special interpretation of sex employed by Lang and 

 borne out by his formulae, his view has several points in common with 

 the hypothesis of chromosomal elimination. It should be noted, 

 however, that there are also differences in the application of Lang's 

 and the present interpretation, when the question of the sex-linked 

 factors is involved, because the two X chromosomes represented by 

 Lang by FG, FG carry many other genes, besides those for sex, even 

 some for secondary sexual characters. Which of these comes to 

 expression in the hybrid gynandromorph depend on which FG is elim- 

 inated and not on the resulting change in balance (epigenetic effects) 

 between the FG's and the MA's. Furthermore, Lang's scheme in- 

 volves the relation between two pairs of chromosomes (four in all) 

 while in the actual case of Drosophila only one pair is needed to account 

 for all the facts. 



Cockayne, in 1915, announced independently the same view of 

 elimination that Morgan had published the year before. He had 

 found several halved gynandromorphs, all of which showed the specific 

 characters of both parents on both sides. Both parental nuclei must 

 therefore have contributed to both sides. He points out that since 

 the division into male and female parts sometimes coincides with 

 other characters the latter must be carried by the sex chromosomes. 



Doncaster, in 1914, described binucleated eggs in Abraxas, each 

 nucleus giving off its two polar bodies and each being independently 

 fertilized. He suggests that gynandromorphs might arise from such 

 eggs, but did not obtain any in the particular lines that showed such 

 binucleated eggs. The two gynandromorphs in Abraxas that Don- 

 caster described later (1917), and which are considered here on page 

 85, he did not attempt to explain by this condition. 



The gynandromorphs of Drosophila have been from the time of 

 then* first appearance in our cultures, about 8 years ago, a subject of 

 general interest and discussion, especially by Muller, Sturtevant, 

 Bridges, and Morgan. Their relation to the gynandromorphs in 

 bees and to the theories of the origin of the latter has been constantly 



