THE 'bar eye' mutant OF DROSOPHILA 



525 



TABLE 9 

 Regression toward the mean of the parental generation 



81.7 



135.5 



Fig. 3 The effect of selection in Plus Line A, at the right, and Minus Line D, 

 at the left. The horizontal lines represent range of facet number, the lowest 

 numbers at the left and the highest at the right. The lowest horizontal line 

 represents the original unselected population, the others, beginning at the 

 bottom, respectively the populations after the first, second and third selections. 

 The extent of overlapping of facet number in each generation is indicated by the 

 overlapping of the two parallel lines. The heavy lines give the progress of the 

 mean values. The numbers are these mean values. A dotted line in every case 

 runs from a mid-parental value, below, to the mean of the offspring, above. 

 On the sides of each dotted line are the lines running from the mid-parental value 

 to the values of the extreme individuals of the offspring. The full data are given 

 in tables 1, 4 and 7. 



