42 



THE ORIGIN OF GYNANDROMORPHS. 



one X with eosin and miniature genes to produce the male parts, which in 

 this case affected visibly only a part of the left eye. 

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No. M, 114. January 23, 1914. C. B. Bridges. Text-figure 22 (diagram). 



Parentage. One of the X chromosomes of the mother contained the gene 

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

 parents were heterozygous for the autosomal recessive 

 gene "whiting," which is a specific modifier of eosin. 



Description. The gynandromorph was somewhat 

 more than half female. The left side of the gynan- 

 dromorph, except for the head, was male, with sex- 

 comb, smaller bristles half-thorax and wing. In col- 

 oration the abdomen was male on the left and female 

 on the right. The genitalia were entirely female. 

 The head had heterozygous bar (female) eyes, which 

 were white-eosin compound (female) in color. A pair 

 of ovaries was present. 



Explanation. An egg containing the X chromo- 

 some with the gene for eosin was fertilized by the 

 X sperm with the genes for white and for bar. 

 Either chromosome may have been the one to suffer 

 elimination; which one it was could not be determined, 

 since the head did not show male parts. 



No. 438. August 16, 1914. C. B. Bridges. Text- 

 figure 23 (diagram). 



Parentage. One X chro- 

 mosome of the mother con- 

 tained the genes for eosin 

 and for vermilion, the other 

 X the gene for white eyes, 

 the male carried the gene for eosin. 



Description. The left side of the gynandromorph 

 was largely male with a white eye (containing a 

 fleck of white-eosin), a sex-comb, and a shorter wing. 

 The right side was female, with a white-eosin com- 

 pound eye, no sex-comb, and a longer wing. The 

 abdomen was banded like a female. When bred as 

 a female the fly gave the classes expected for a 

 white-eosin compound. No sections were made. 



Explanation. An egg containing the X chromo- 

 some with the gene for white was fertilized by an X 

 sperm carrying the gene for eosin. The latter the 

 paternal chromosome suffered elimination, leaving 

 the white-bearing X to produce the male side. 

 The color of the eye on the female side was white-eosin 

 compound, which is the expected result for the two 

 X's involved. 



TEXT-FIGURE 22. 



The X chromosome of 



TEXT-FIGURE 23. 

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