428 p. W. WHITING 



and sootj^ and if cleft is recessive as the Fj generation apparently 

 indicates, no cleft sooty should appear in F2. If the linkage was 

 partial the ratio of sooty to type should be higher than that of 

 cleft sooty to cleft. Considering only the gray, since black in- 

 troduces a further complication, which is entirely explained 

 below, there were 249 sooty to 350 type, or 71 per cent; and 34 

 cleft sooty to 53 cleft, or 68 per cent. The difference between 

 the ratios is not great enough to be significant. Although the 

 classification was admittedly arbitrary as regards sooty, any 

 error would not affect its relation to cleft. It may therefore 

 be concluded that no linkage appears between cleft and sooty. 

 3. Apparent complications of black and sooty. In the black 

 moths of the F2 generation from pair (109) accurate separation 

 of sooty and non-sooty was uncertain as in the gray. It has 

 been possible to test for linkage of cleft with sooty and with 

 black. As regards relations between black and sooty, however, 

 complications arise since the character affected is the same, 

 namely, the color of the wings. If the classification were not 

 disturbed by this fact and if no linkage existed, the ratio of sooty 

 to type should equal the ratio of sooty black to black. There 

 are recorded 283 sooty, 403 type, 19 sooty black, and 198 black. 

 This gives 70.2 per cent as the ratio of sooty to type and only 

 9.6 per cent as the ratio of sooty black to black. It is evident 

 from a comparison of these two ratios that there is either close 

 linkage between sooty and black or else disturbance in dominance. 

 Results recorded below prove that the latter is the case. 



D. Analysis of the gradations of sooty base 



It will be recalled that the variation called dark mid-area has 

 an effect somewhat the reverse of sooty base. Dark mid-area 

 appeared in many moths of the Fo generation from (109) and 

 doubtless accounts very largely for the difficulty in distinguishing 

 sooty from type. 



A pair of moths in which the primaries had rather dark bases 

 and which were probably sooty with dark mid-area produced 

 72 sooty, 77 type, and 10 that were intergrading between sooty 



