Description of Characters. 



33 



arching of the wing as well as by the angular position in which the wing is held out 

 from the body. None of these characters is constant, and for this reason considerable 

 difficulty is experienced in classifying the flies. Owing to this and to the fact that 

 double flies have very poor viability, the stock has been discarded. 



Origin. — (V 1169.) Double first appeared in a pair mating, both parents evi- 

 dently having been heterozygous; the offspring were 57 double (28 9 9:29cfcr), 

 and 190 not double (89 9 9 : 101 cf d^). 



Table 4. — Chronological list of autosomal characters in Drosophila virilia. 



Character. 



Sym- 

 bol. 



Parts 

 affected. 



Link- 

 age 

 group 



First 

 observed. 



Found 

 by- 



Record. 



Confluent. . . . 

 Concave 



Steel 



Acute 



Branched 



Fused 



Telescoped . . . 



Scaly 



Double 



Hump 



Minus 



Capsule 



Hunch 



Pinched 



Interrupted . . . 

 Approximated, 

 Net 



Spine 



Spread 



Broken 



Garnet 



Extra 



Ruffled 



C 



CO 



St 



ac 

 B 

 fu 



t 



S 



de 



hp 



mi 



cp 



h 



P 



i 



a 



Nt 



en 

 sp 

 b 

 G 

 E 

 ru 



July. 1914 



Sept., 1915 

 Feb., 1916 



Do 

 Sept., 1916 

 Nov., 1916 

 Feb., 1917 

 July, 1917 



Do 

 Mar., 1919 



Do 

 Apr., 1919 

 May, 1919 

 June, 1919 

 Sept., 1919 



Do 



Do 

 June, 1920 

 Mar., 1921 

 May, 1922 



Do 

 June, 1922 



Do 



Metz 



Metz 



Metz 



Metz 



Metz 



Metz 



Metz 



Metz 



Metz 



Metz 



Metz 



Metz 



Metz 



Metz 



Mason 



Mason 



Metz 



M. Demerec 



Moses 



Moses 



Metz 



Metz 



Metz 



Metz, 1916, p. 693 



Metz, 1916, 

 Metz, 1916, 

 c stock. 



V 601. 606. 



V 778. 

 V974. 



V 1128. 



V 1169. 

 Hyde stock. 

 L 22. 

 L92. 



L 176. 

 L252. 

 E 15. 

 E 15. 



L462. 

 P stock. 

 P 577. 

 M 66. 

 M 13. 

 M 21. 



M 113. 



597, 

 698, 



Broken (b). (Plate 3, Figures 8 and 9.) 



Description. — The character takes its name from the break in the cross-veins. 

 The posterior cross-veins are usually lacking, but may be broken, or, in rare cases, 

 one may be intact but thin in the middle. The anterior cross-veins are sometimes 

 absent or broken, but not constantly so. Frequently, the distal end of the third 

 and fourth veins is thin, and occasionally these veins fail to reach the wing-margin. 

 In addition to the effects on the veins, a characteristic soft, wavy, and glossy appear- 

 ance of the wing as a whole may usually be noticed. In most of the flies the posterior 

 cross-veins are entirely gone, as they are in crossveinless flies. When this is not the 

 case, the end of the vein nearest the fourth vein is usually gone, resulting in a con- 

 dition almost indistinguishable from that found in interrupted flies (fifth chromo- 

 some). The frequency of these types may be judged roughly from the following 

 count of 50 flies taken from a stock bottle: in 46 specimens both posterior cross-veins 

 were entirely gone, in 3 both posterior cross-veins were broken (end next to fourth 

 vein gone), and in 1 one posterior cross- vein was gone while the other was intact, but 

 thin in the middle. 



