Description of Characters. 



47 



Branched (B). (Plate 4, Figures 1, 2, and 3.) 



Description. — Branched is a dominant, irregular in its manifestation and incon- 

 stant in its appearance. It is usually characterized by a branch extending distally 

 from the posterior cross-vein. This is often accompanied by slight protuberances or 

 branches above the second vein, near its tip, in the region affected by confluent, 

 triangle, and extra. The branch from the posterior cross-vein may be long or short, 

 or may not connect with the cross-vein. When this happens a short vein lies free 

 in the cell beyond the posterior cross-vein. Sometimes only a vestige of this is 

 present, and frequently no extra veins appear. Homozygous flies are more extremely 

 affected, on the average, than heterozygous ones, but the two types over-lap and 

 can not be differentiated. Homozygous branched flies are viable and fertile and 

 breed readily in pure stock. 



Origin. — (V 601, V 606.) Several branched flies were found in a stock bottle. 

 From these, two males were out-crossed and gave respectively (V 601) 60 branched, 

 79 wild-type, and (V 606) 33 branched, 67 wild-type, showing the dominance of 

 branched. 



Approximated (a). (Plate 4, Figures 5, 7, and 8.) 



Description. — The nature of this character may best be appreciated by an ex- 

 amination of figure 5, plate 4, and a comparison of the wild-type wing shown in 

 figure 1 of plate 2. The name is derived from the fact that the two cross-veins are 

 closer together than usual. This is apparently due almost entirely to a modification 

 of the posterior cross-vein. The junction of this vein and the fifth is slightly nearer 

 the base of the wing than usual, but is not moved much. The junction with the 

 fourth vein, however, is shifted considerably toward the base, making the distance 

 between the cross-veins along the fourth vein about two-thirds as long as usual. 

 In wild-type flies the segment of the fourth vein between the two cross-veins is con- 

 siderably longer than the apical segment of the fifth vein. In approximated flies it 

 is shorter. In the latter the posterior cross-vein is also usually bent in an S shape 

 instead of being straight. 



In flies heterozygous for approximated the condition 

 is somewhat intermediate (plate 4, fig. 8), but nearer 

 wild-type than homozygous approximated. Such flies are 

 readily distinguished from approximated, but it is 

 difficult to separate them from wild- type. The curved 

 cross-vein is frequently found in heterozygous flies. It 

 is not a definite enough characteristic, however, to per- 

 mit the use of approximated as a dominant. 



Origin. — See under interrupted (p. 46). 



Ruffled (ru). (Figure 12.) 



Description. — In ruffled flies the tips of the dorso- 

 central bristles and the hairs near them are curved 

 forward and toward the midline of the thorax, as if 

 they had been brushed back toward the head and in 

 from the sides. This gives the thorax a ruffled appear- 

 ance. The viability of ruffled flies is very good, making the character one of the best 

 for linkage studies. 



Origin.— {M 113.) 24 ruffled flies (both sexes) appeared in the progeny of two 

 pairs from a previous mating of two pairs. At least one male and one female of the 

 former must have been heterozygous for the new character. 



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Fig. 12.— Ruffled. 



