56 



THE ORIGIN OF GYNANDROMORPHS. 



The genitalia were largely male, but had female parts on the right side. A 

 pair of rudimentary ovaries were present. There were sex-combs on both 

 forelegs, so that the ventral side of the thorax was entirely male. The fly was 

 tan throughout. 



Explanations. — An egg containing a cross-over chromosome with the genes 

 for notch, tan, and vermilion was fertilized by an X sperm carrying eosin, 

 tan, and vermihon. Elimination of the maternal X was followed by shifting 

 of the cleavage nuclei. 



N 



t 



w" 



t 



w^ 



t 



No. 983. December 20, 1914. C.B. Bridges. Text-figure 47 (diagram). 



Parentage. — One of the X chromosomes of the mother carried the genes for 

 white and for bar, and the other X the gene for eosin. The father was 

 miniature. 



Description. — The separation of the sex-characters is very complex. The 

 dorsal parts of the thorax and the wings are, from their size, female ; the lower 



Text-figure 45. 



TEXT-riGURE 46. 



Text-figure 47. 



part of the thorax, from the presence of sex-combs on both forelegs, is male. 

 The abdomen is female on the left half and male on the right. The genitalia 

 are female. The abdomen contained a pair of ovaries as seen through the 

 body-wall and in sections. The fly was sterile. The head was entirely male, 

 with white eyes, not-bar. 



