OF MUTANT CHARACTERS. 



295 



culture 2671 (A. H. S.). The relationship between the first cultures 

 in which the character was observed is shown in the following pedigree : 



2568 a 



2608 



I (Daughters of 

 2617 2568a.X 



2672 



(\Vild-type ? 

 s e s s XeSr 

 brother) 



The four cultures starred in the above diagram gave the following 

 numbers of offspring: 



TABLE 139. 



The viability of the dachsoid flies was evidently very poor; and the 

 adults were so weak that all attempts to breed from them failed. For 

 this reason the character was discarded after very little had been done 

 with it. 



Since three daughters of the original pair produced dachsoid descend- 

 ants when mated to different stock males, it is practically certain that 

 one of the parents of 2568a (A. H. S.) was heterozygous for the dach- 

 soid gene. It is not possible to determine which parent, or how long 

 the character had been in the stock. No other experiments involving 

 these (or any other) stocks have produced dachsoid flies. 



DESCRIPTION OF DACHSOID. 



As shown in figure 86, the dachsoid flies are small and ail parts head 

 thorax, abdomen, wings, and legs are markedly shortened, as though 

 from pressure. The particular specimen drawn was sepia spineless 

 kidney sooty rough, as well as dachsoid, and the short bristles and 

 abnormal eyes are due not to the dachsoid but to spineless and kidney 

 rough. The wings, besides being shortened, are actually broader than 

 normal. They are held out at a wide angle from the body and have 

 a tendency to curve. The posterior cross-vein is almost entirely gone 

 and frequently the anterior cross-vein is similarly affected. A char- 

 acteristic feature is a short branch on the second, longitudinal vein 

 similar to the remnants of the cross-veins. The hairs on the costal 

 vein before the apex of the first vein stand out from the vein more than 

 in wild-type flies. 



