46 



THE ORIGIN OF GYNANDROMORPHS. 



Explanation. An egg containing an X with a gene for forked was fertilized 

 by a bar X sperm. The paternal X with bar was eliminated, leaving the 

 head male and forked. 



TEXT-FIGURE 30. 



No. 71. October 23, 1917. E. M. Wallace. Text-figure 31 (drawing). 



Parentage. Pure stock of bar. 



Description. A female was observed that had a short left wing. Closer ex- 

 amination showed that the bristles on that side of the thorax and head were 

 shorter and that the left side of the head was slightly contracted and the eye 

 smaller. It is probable that the left side of head and thorax (dorsally) were male. 



No. 7530. August 18, 1917. C. B. Bridges. Text-figure 32 (diagram). 



Parentage. One of the X chromosomes of the mother carried the gene for 

 facet eye and the other X the gene for notch wings (dominant). The X 

 chromosome of the father carried the gene for facet. 



Description. The left side of the gynandromorph was male, with a shorter 

 wing, sex-comb, and smaller eye, whose markedly faceted eye was character- 

 istic for that character as it appears in the male of the mutant type. The 

 female side had a faceted eye of the female type, which is far less marked. 

 The abdomen was banded as in the female, but below a penis was present. 

 Testes were found on both sides, with an abundance of sperm. 



Explanation. An X egg-carrying facet was fertilized by the X sperm- 

 carrying facet. Elimination of either occurred. The gonads were formed 

 from a male cell. Very frequently a male-appearing abdomen contains 

 ovaries; only very rarely does a female-type abdomen contain testes. 



