DILUTION EFFECTS IN CERTAIN EYE COLORS 433 



tion Vestigial wing/ the initial letter (v) and a second convenient 

 letter (g), writing the (g) as a sub-letter in smaller type thus: 

 (vg). The dominant form of the determiner concerned in a 

 recessive mutation we designate by the corresponding capital 

 letter, thus, Vg = normal allelomorph, and p = pink factor, 

 P = its normal allelomorph. In the case of multiple allelo- 

 morphs, the first modification of the series will usually supply 

 the initial symbol for the whole series, and the third and other 

 allelomorphs will receive as modifications of that symbol a sug- 

 gestive letter written as an exponent. Thus white is represented 

 by (w), normal by (W), and eosin by (w^). 



For simplification we put in the formula for an eye color only 

 such symbols as directly concern the cross we intend to make. 

 Thus the full formula for vermilion. is X W v P etc. X W v P etc. 

 and of pink X W V p etc. X W V p etc. but if in the analysis 

 of the cross vermilion by pink we discard from both formulae all 

 factors not under comparison except the sex differentiator, thus, 

 X V P — X V P (vermilion 9 ) and X V p p (pink cf ). 



In our tables of analysis, there appears in the formula for the 

 male a long dash to represent the fact that half the gametes 

 formed by the male carry no sex chromosome, for example, the 



vermilion pink male forms the two gametes X v p and p. 



The vermilion pink female forms the gametes X v p and X v p. 

 The formulas for Fi and F2 zygotes are generally written in this 

 paper with the letters for the allelomorphs in vertical alignment. 



In the course of our former work various heterozygous reds 

 have been examined, namely, red heterozygous for pink, ver- 

 milion, white, and for both vermilion and pink, but no difference 

 was observed between these and the red eye color of the wild 

 fly. All of these combinations appear in ''An attempt to analyze 

 the constitution of the chromosomes on the basis of sex-linked 

 inheritance in Drosophila." In order to see whether differences 

 would appear if the reds were heterozygous for other factors, or 

 combinations of factors, the following series of experiments was 

 made. 



