270 



THE SECOND-CHROMOSOME GROUP 



unfavorable conditions could be obtained with streak, especially as 

 long as the calculations are restricted to the flies which actually show 

 the streak character above a certain definite grade of development. 

 A back-cross was therefore undertaken between star and streak, between 

 streak and dachs, and between dachs and purple — all in the same 

 experiment. The advantage of purple is that its locus is securely 

 mapped in the main body of loci, and its presence serves as the con- 



Table 122. — Summary of all cross-over data involving star. 



Loci. 



Star streak . 



Star cream L 

 Star truncate 

 Star dachs. . 



Total. 



396 



389 

 549 



Star black. . 



Star trefoil . . 

 Star apterous 



Star purple. 



96 



152 

 1,617 



369 



211 



1,027 



3,472 



1,352 



496 



865 

 690 



13,104 



Cross- 

 overs. 



16,507 



154 

 205 



6,766 



1,027 



362 



63 



86 

 149 



31 



53 

 425 



112 



57 



271 



949 



522 



203 



315 

 266 



4,944 



Per 



cent. 



15.9 



22.1 

 27.1 



32.3 



34.8 

 26.3 



30.4 



27.1 



26.4 



Date. 



27.3 



6,250 



65 



88 



8,155 



3,010 

 413 

 138 



38.6 



40.9 



36.4 

 38.6 



37.7 



37.9 



42.2 



42.8 



3,561 



44.5 

 40.2 

 38.1 



Aug. 24, 1916 



Oct. 20, 1916 



May — , 1917 



Sept. 12, 1915 



Sept. 12, 1915 

 Sept. 15, 1915 



Oct. 6, 1915 



Nov. 18, 1915 



Aug. 24, 1916 



Jan. 1, 1915 



Oct. 23, 1915 



Oct. 26, 1915 

 Dec. 22, 1915 



By- 



Bridges 



Do. 



Wallace 



Do. 



Do. 

 Do. 



Do. 



Do. 



Do. 



Bridges 



Do. 



Do. 

 Do. 



Reference. 



S': ^ — Plb. C, Sk flies only; 



Crb', 



Std 



S' 



crb 



4999-5110. 

 B.C.; 5593+5824. 



Snub; p. 143, this paper. 



dr, — F2, dachs flies; 2141- 



d 2216. 



idem, not-dachs flies. 



S'; — B.C.; 2146-2305. 

 d 



dl; 



dl; 



S' 



dl 



F2; 2217-1659. 



S' 



dl 



B.C.; 2460. 



S'; §L-—2l B.C.; 4999-5110. 



Std 



Px\ 



S' 



b Px 



B.C.; 1921-24. 



A; 



S' 



b fr 



S' 



B.C.; 2282-84. 



43.7 



vgn; : B.C.; table 123, 



b vgu this paper. 



di; ^1A_ B.C.; 2679-7085. 



J. E. Z., '17, p. 147; tempera- 

 ture; — B.C.; table 7 (22"). 

 be 



86(27°), 86(22°). lll(22°), 173. 



Op; — 

 S';^ 



F2 ; p. 239, this paper. 



Op 



B.C., lsts;1836- 



Pr c Sp 1894 



S'-— ^B.C; 4999-5110. 



St4 



B.C., construction; 

 Pr 7391, 7392. 



5';^ 



