54 THE ORIGIN OF GYNANDROMORPHS. 



Description. The gynandromorph was entirely female, except for the tip 

 of the abdomen below, where a perfectly normal penis and male genitalia were 

 found. The anal prominence and the parts immediately surrounding the 

 genitalia were also male. The posterior ventral plate was male type, being 

 broad, rounded, and hairless. 



No. 1221. February 2, 1915. C. B. Bridges. Text-figure 42 (diagram). 



Parentage. The mother was an XXY wild-type female, one of whose X 

 chromosomes carried the gene for eosin, the other X only wild-type genes. 

 The father was bar. 



Description. The gynandromorph was bilateral, except for the head, 

 which was entirely female, with red bar eyes of the heterozygous type. The 

 right side of the thorax dorsally was male, with shorter bristles and very small 

 wing (abnormal). There were no sex-combs. The right side of the abdomen 

 was male in coloration, and the genitalia were almost entirely male. There 

 was a pair of testes with ripe spermatozoa. The two halves of the thorax 

 failed to come together and the male and female parts were unfused. 



Explanations. The egg carried the eosin X and may or may not have con- 

 tained a Y. The sperm was the X sperm carrying bar. Elimination of either 

 X occurred. It is possible that the spina bifida condition may have been a 

 result of the gynandromorphism. 



No. 1892. July 19, 1915. C. B. Bridges. Text-figure 43 (diagram). 



Parentage. The mother was a wild-type XXY female, which was an ex- 

 ception from "high" non-disjunction. One X carried the gene for eosin, the 

 other the genes for vermilion and forked. The father was bar. 



Description. The fly was female throughout, except that the left side of the 

 abdomen, especially at the tip, showed male coloration and the genitalia 

 were entirely male. The eyes were heterozygous bar (female). 



Explanation. An egg with one X (either) and with or without a Y (even 

 chance) was fertilized by an X sperm carrying the gene for bar. Elimination 

 of either X occurred. 



No. 7673. October 16, 1917. C. B. Bridges. Plate 4, Figure 3 (drawing). 



Parentage. The mother was an eosin-eyed XXY exception from a special 

 strain of "high" non-disjunction (H e ), which had arisen by equational non- 

 disjunction from the regular high strain. One of her X chromosomes carried 

 the gene for eosin and the other the genes for eosin and forked. The father 

 was bar. 



Description. The male parts of the gynandromorph constituted the entire 

 head, which had eosin eyes of the male type and forked bristles; the left 

 side of the thorax, which had forked bristles, was smaller, with a male-size 

 wing and a sex- comb and a slight patch of male tissue at the tip of the ab- 

 domen, but on the right side, not the left. The abdomen was twisted, as it 

 usually is when bilateral, but since the bristles were not forked, the male 

 parts, if any, must have been below or internal. The right wing was abnormal. 



Explanations. An X egg carrying the genes for eosin and forked was fertil- 

 ized by the X sperm carrying the gene for bar. Whether or not a Y was 

 present in the egg is not known (chances even). Elimination of a paternal 

 bar X occurred. 



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