130 The Inheritance of Wing -Colour 171 Lepidoptera 



the maximum of the curve denotes that percentage of black which occurs 

 most frequently. In the case of the curves showing the distributions of 

 the black values, the figures along the base line denote the number 

 of individuals. Each individual is represented by a cross, a circle or 

 some other sign, which is the same for both sexes of any given family. 

 The percentage of black in the pattern is shown on the perpendicular 

 at the left-hand side. The name of the family and the sex are written 

 against each curve, whereas the percentage of black in the grossulariata 

 pattern of each parent is shown by an arrow at the correct point on 

 the right-hand side. 



1) 30 



9 Parent of '19 Z Percentarje of Black 



Text-fig. 2 (cf. Text-lig. 1). Diagrams showing the frequency distribution of the values 

 for the black pattern in the ^ ^ and ^ '^ ol the families shown in Text-fig. 1. 



Text-fig. 3 shows a group of families from a dark strain of Mr New- 

 man's, which carries the factor, I, leading to an increase of the black 

 pattern, but not the factor for varleyata, thus showing conclusively the 

 independence of these two factors. The appearance of these curves is 

 very different from that of '19 Z (Text-fig. 1), and the salient points are 

 best seen in the frequency distribution. Text-fig. 4, in which the males and 

 females of all three families are combined in two curves. The average 

 extent of the black pattern is obviously greater than in type strains, and 

 this increase of black is greatest in the curve for the males, as may be seen 

 from the fact that its maximum falls to the right of that of the $ $ curve. 

 The average value for the black pattern, when both </ ^ and $ $ are con- 

 sicjered, is about 80 per cent. ; that of the $ % about 78 per cent., and that 



