THE ORIGIN OF GYNANDROMORPHS. 



29 



of 152 black 9 and 147 black cT, with no yellow-black offspring. Evidently, 

 then, the testes came from a cell which had not mutated. While the 

 "brown" color of the mosaic was like that produced by yellow acting with 

 black, it is possible that the mutant gene was not the yellow already known, 

 but a new yellow. 



(3) Among the grandchildren of the last somatic sport a fly was 

 found with a wing of an unusual type (text-fig. 9). This wing was 

 about half the usual length and had almost exactly the form of min- 

 iature, but there was none of the dark color normally present in 

 miniature wings. This wing seems to have been a new mutant type, 

 the mutation having occurred in the early embryonic cells of the fly. 

 There have been 

 quite a number of 

 such occurrences, 

 some, as in the 

 present case, giv- 

 ing striking differ- 

 ences. 



(4) A fly ap- 

 peared in vestigial 

 stock (August 13, 

 1912) with one 

 normal wing (text- 

 fig. 10). It was 

 described as a case 

 of somatic atav- 

 ism. An alterna- 

 tive view is also 

 possible, viz, that 

 a somatic muta- 

 tion occurred else- 

 where, i. e., in an- 

 other chromosome or in another region of the second chromosome, 

 of such a sort that it neutralized the effect of both genes for vestigial. 

 In the cells containing this mutant gene the conditions for normal 

 wings are again restored. 



(5) and (6) Two further cases of mutation in the male were found 

 by Sturtevant (not published); both were males throughout; one had 

 forked bristles on one side of the body, although there were no forked 

 flies in the immediate ancestry. The other had a dark body-color 

 on part of the thorax, there being no sex-linked dark body-color in 

 the pedigree. Neither fly was tested. 



(7) In a stock pure for red eyes, miniature wings, and yellow body- 

 colo r a fly appeared with all the characters of its race except that one 

 eye was white with a fleck of red at its posterior edge (text-fig. 11). 



TEXT-FIGURE 8. 



TEXT-FIGURE 9. 



