No. 644] MUTANT CHARACTERS IN DROSOPHILA 225 



veins at a level about half way between the anterior and 

 posterior cross-veins. This vein, when not wholly formed 

 as a cross-vein, is often indicated by short pieces of dis- 

 connected vein. 



The fusion of the second and third veins and the ex- 

 tension of at least one wing are constant characters as 

 far as observed. The latter forms the easiest basis of 

 distinguishing this mutant. The females are more ex- 

 treme than the males in all four of the changes involved. 

 Triple suggests the melanogaster mutant, bifid, by its 

 extended wings, fusion of the veins at the base of the 

 wing, and the shortening of one of the veins, although 

 the short vein is the fourth in bifid and the third in 

 triple and the third vein of bifid is thickened at the distal 

 extremity. 



Ori^w.— Triple was first noticed in the offspring of 

 a female out-crossed from wild stock. Half the males 

 were triple. On investigation it was found that several 

 bottles of wild stock contained similar males. 



Triple males were found six months later in stump 

 stock. Crossed to the original triple stock, these males 

 produced triple female oflFspring in the generation. 

 The possibility of contamination of the stump stock can 

 be eliminated since the triple males found in the stock 

 were also stump, and there were no cultures containing 

 triple stump flies in the laboratory. 



The Deformed Allelomokphic Series 

 1. Deformed {d) 

 Description— Betormed, which involves many parts 

 of the body (Fig. 9), shows sexual dimorphism. In the 

 male the eye is about two thirds the normal size and very 

 rough ; in the female the eye is normal in size and only 

 slightlv roughened. In both sexes the bristles are ab- 

 normally long and irregularly bent. The thoracic hairs 

 are badly disarranged in both sexes, but the effect is 

 very much more exaggerated in the female than in the 



