132 The Inheritance of Wing-Colour in Lepidoptera 



of the cf </ about 85 per cent. If the families are considered separately, 

 the darkest parents, as might be expected, appear to have the blackest 

 offspring. This may be seen by a glance at the values for each parent, 

 shown by the arrows on the right-hand side, where families '18 A and 

 '18 G (Text-fig. 3) seem to have the darkest parents. The (/* parent of 

 '18^ was unfortunately lost, but a note remains describing it as rather 

 darker than type, and probably with a black value of about 60 per cent. 

 The curves shown in Text-fig. 5 represent families which carry both the 

 factor, I, leading to an increase of the black pattern, and the factor for 



f.-~ 



^Hs^ 



'••..^'16 Z^x ^-C^-^^^PCTCT 



+s^ '■'.': d'c? '18 n^ytj ° — »-, 



Vl8\ -.'16 ZQ9 



■'■■••••.\.QQ+ \ 



\--.... '■••.'.18 UeTo- 



'i8p\ '■••.; 



99 



■■,'18 u99 



Parent of '18 R 



Parents of '18 P, 

 and '16 Z 



Parent of '18 U 



No. of Insects 



Text-fig. 5 (cf. Text-fig. 6). Curves showing the distribution of the values for 

 the black pattern inFi ^ ^ and $ $ , from the cross grossulariata 5 x var- 

 leyata ^ {'16 Z and '18 U). Similar distributions are given for grossu- 

 lariata ^ ^ and $ $ from the cross F^ x varleyata ('18 P and '18 jR). The 

 effect of the factor I, which leads to an increase of the black pigment, can 

 be seen in both sexes, but more so in the ^ ^ than in the $ $ . 



varleyata. Families '\Q Z and '18 C/" are the F^ generation from the cross 

 grossulariata % x varleyata (/ , and their average black value is greater 

 than in type specimens, and also greater in the </ cT than in the $ $ . The 

 two other families in the same figure, '18 P and '18 i^, are grossulariata 



