70 



THE REPORT OF THE 



No. 36 



Experiments with the English Currant Moth. 



The work of Doncaster and Raynor (1908) in connection with the crossing 

 of two varieties or sub-species of Abraxas, gross ulariata and lacticolor, was im- 

 portant in that it furnished additional, evidence that certain characters are some- 

 times linked up with sex or with the sex factor. For example, color-blindness in 

 man seems to be linked up with sex. Men cannot hand on the defect without 

 having it, whilst women can. Doncaster and Raynor's results are explained on the 

 assumptions that the female is heterozygous for sex, femaleness being dominant, 

 the male a homozygous recessive, and the factor for color for grossulariata is 

 dominant. The gametic formula.^ for the crossings are given below: 



C. = dominant factor for color (grossulariata.) 



c. = recessive factor for color (lacticolor.) 



F.f. = sex factors in female. 



F.F. = sex factors in male. - • 



Case I. Grossulariata (male) x lacticolor (female). 



CF CF z= male gametes. 



Female 

 gametes 



CF 



cf 



= all grossulariata (heterozygous) 

 50% female, 50% male. 



Case II. Fi Grossulariata (male) x Fi Grossulariata (female), 

 CF cF = male gametes. 



Female 

 gametes 



Cf 



cF 



50% grossulariata females (i^ nor- 

 mal, % heterozygous). 25% gross, 

 males (heterozygous, 25% lacticolor 

 male (normal). 



Case III. Fi Grossulariata (male) x lacticolor (female). 



CF cF = male gametes. 



Female 

 gametes 



cF 



cf 



=z 25% gross, female (heterozygous), 

 25%' gross, male (heterozygous), 

 25% lact. female (normal), 25% 

 lact. male (normal). 



Case IV. Lacticolor (male) x Fi Grossulariata (female), 



cF 



cF 



Female 

 gametes 



Cf 

 cF 



male gametes. 



^^ 50% gross, heterozygous females. 

 50% lact. heterozygous females. 



An interesting case arose in the reciprocal of- Case I when a pure wild 

 grossulariata (female) was crossed with a lacticolor (male). The result was the 

 same as in Case IV, showing that the wild grossulariata female is heterozygous 

 with regard to that color. 



