THE ORIGIN OF GYNANDROMORPHS. 35 



Approximately Bilateral Gynandromorphs. 

 No. Giad2. Feb, 1914. E. M. Wallace. Plate 2, Figure 1 (colored drawing). 



Parentage. — The mother wavS a white-eosin compound female from the cross 

 of a yellow white female to an eosin male. The father was a yellow white male. 



Description. — The entire head, the right half of the thorax and of the ab- 

 domen, the right wing, and all of the right legs were gray and female. Both 

 eyes were white-eosin compound and therefore female, which was in agree- 

 ment with the gray color and black bristles of the whole head. The genitalia 

 were apparently entirely female. The left side of the thorax and of the 

 abdomen, the left wing, and all of the left legs were yellow in body-color, 

 smaller, and male. There was a sex-comb on the left side only. The gynan- 

 dromorph failed to produce offspring when tested. 



Explanation. — An egg with the eosin-bearing X was fertilized by the X 

 sperm bearing the genes for yellow and white. The zygote was therefore 

 female, and the female parts of the gynandromorph have this constitution. 

 At the first segmentation, division elimination of a maternally-derived eosin- 

 bearing X occurred, giving rise to a cell with only a yellow white X. The 

 parts descended from this cell were male and showed the yellow body-color 

 corresponding to the yellow white chromosome. Since neither of the eyes 

 was male, the white eye-color had no chance to show on the left side. 



w 

 I 



y w y w 



No. GaCisa. Feb. 1914. E.M.Wallace. Plate 2, Figure 2 (colored drawing). 



Parentage. — A mass culture of the white-eosin compound females (eosin in 

 one X and yellow white in the other, from gynandromorph G2C19 above) out- 

 crossed to yellow white males produced a further gynandromorph (G2C190). 



Description. — The gynandromorph, while yellow and white throughout, was 

 a strict bilateral gynandromorph, including genitalia and antennae. The right 

 side was male throughout, as evidenced by sex-comb, smaller size of bristles 

 and of all parts such as eye, thorax, wing, legs, and abdomen, and by the male 

 coloration of right side of the abdomen. The gynandromorph was tested but 

 gave no offspring. Sections showed slightly developed ovaries on both sides. 



Explanation. — An egg containing the X with the genes for yellow and white 

 was fertilized by an X sperm likewise carrying the genes for yellow and white. 

 Elimination at the first segmentation division of a maternal or of a paternal 

 X, gave a cell with a single X, from which is descended the male right side. 



y w yw 



yw 



No. 77. March 10, 1914. C. B. Bridges. Text-figure 14 (diagram). 



Parentage. — The mother was homozygous for eosin and heterozj'gous for a 

 non-sex-linked gene "cream," which is a specific dilutor for eosin (Bridges, 

 1916). The father had the same constitution. 



Description. — The gynandromorph was completely bilateral "from head 

 to tail." The right side was male with a sex-comb and smaller jKirts. The 

 abdomen had the female coloration above, but below was divided iialf and 

 half, as were the genitalia. The eyes were both "cream," that is, of diluted 



