230 THE AMERICAN NATURALIST [Vol. LVI 



rough on one X-chromosome and stump on the other. 

 The mutation to short evidently affected a locus of the 

 orange rough chromosome not far from the stump locus. 

 Several sister cultures were examined, but no short flies 



2. Sliori-2 {sluj 



Description. — Short-2 is the most extreme of the 

 series. In the females the second, fourth, and fifth veins 

 are very short, the fourth and fifth often not reaching 

 as far as the posterior cross-vein. In cases in which they 

 extend beyond the cross-vein, this vein is broken. In the 

 males the fourth and fifth veins are about three quarters 

 the normal length, and the posterior cross-vein is broken 

 (Fig. 14). The males are indistinguishable from those 

 of short-3. 



Origin. — A single male was found in small-bristle 

 rough stock. 



3. Short-3 (sk,) 



Description. — Short-3 is al)out the same in both sexes 

 (Fig. 15). The second vein is very short, and all the 

 others are about three quarters the normal length. The 

 jDOsterior cross-vein is usually broken. 



Females containing any two of these three allelomorphs 

 are intermediate between the two used, with perhaps a 

 closer resemblance to the more extreme member of the 

 pair. 



Origin. — Several males were found in scute stock. 

 Mondn im) 



Description. — Morula involves a partial roughening of 

 the eyes which is due to a consolidation of a group of 

 facets, especially in the central area of the eye, suggest- 

 ing the lozenge of melanogaster. The viability of this 

 stock is very poor, and the double recessives of morula 

 and any other mutant character rarely survive. 



Origin. — At least five males were obtained from a mass 

 culture of three pairs which carried rough. The classi- 



