48 THE ORIGIN OF GYNANDROMORPHS. 



Gynandromorphs Mainly Male. 



No. GiAboCaz. March, 1914. E. M. Wallace. Plate 2, figures 6 and 6a 



(colored drawings). 



Parentage. — The mother was a yellow white female, a daughter of gynandro- 

 morph GiAb2C. The father was an ebony (third-chromosome) male. This 

 mating was part of the second of the tests specifically designed to show 

 the absence of elimination of autosomes in the production of gynandromorphs. 



Description. — The gynandromorph was mainly male, with only the head 

 and genitaha female. The color of the entire thorax, abdomen, legs, and 

 wings was yellow, and correspondingly the bristles of these parts were brown. 

 These yellow parts were male, as proved by the sex-combs on both forelegs, 

 by the small (male) size of the bristles, of the thorax, and particularly of the 

 abdomen, and by the male coloration and shape of the abdomen. However, 

 the genitalia were an exception, for the anal prominence and the ovipositor 

 were purely female in structure and bore black spines which showed that the 

 body-color was wild-type. The head was entirely female, as proved by its 

 large size, the wild-type color with black bristles, and by the red eyes. Thus 

 the head and genitalia — the two ends of the fly — were female and all the 

 region between was male. 



Explanation. — An egg carrying the genes for yellow and white was fertilized 

 by sperm carrying only wild-t>T)e genes in the X. EUmination of a paternal 

 X occurred and subsequent shifting isolated a female cell which gave rise to 

 the genitalia. The absence of ebony proves that the third chromosome did 

 not undergo elimination. 



y w y w 



No. X2. February 1914. E. M. Wallace. Text-figure 33 (drawing). 



Parentage. — Gynandromorph X2 appeared in a mass-culture, the mothers 

 of which carried yellow and white in oneX and eosin in the other; the fathers 

 were yellow- white. 



Description. — The gynandromorph was mainly male. The female parts 

 were confined to the abdomen, which had female coloration on the left side 

 and apparently male on the right. The abdomen was twisted to the right, 

 which also suggests that the right side 

 was male. However, the genitalia re- 

 versed this relation, the right side 

 being largely female, with an anal 

 prominence of female type; the left 

 side was male and there was a median 

 penis. The abdomen was of large size 

 and a pair of ovaries could be clearly 

 seen within. The thorax and head were 

 entirely male, as evidenced by their size 

 and the type of bristles and the pres- 

 ence of sex-combs on both forelegs. 

 The eyes were both white and the body- Text-figure 33. 



color was yellow throughout. 



Explanation. — A yellow white X egg was fertilized by a yellow white X 

 sperm. EUmination of either X occurred. An alternative explanation is 

 that the egg was fertilized by a Y sperm giving a yellow white male. Somatic 

 non-disjunction resulted in a cell with both daughter X's present, and this 

 gave rise to the female parts. 



