VARIATION AND HEREDITY 



219 



Filial Regression. Gallon also worked out, by 

 statistical methods, a law which he named the law 

 of filial regression. If we take the mean height 

 of a group of fathers, selected because they are 

 more than normally tall, and compare it with the 

 mean height of their sons, we shall find that the 



Inches 



73 



63 



FIG. 78. Scheme to illustrate Galton's Law of Regression. (From 



Walter.) 



latter average nearer mediocrity ; that is, they " re- 

 gress " toward the normal. Regression does not 

 mean degeneration, but merely a shifting toward the 

 mass-center of the type. It may be upward as well 

 as downward, i.e. the sons of short fathers, on the 

 average, tend to be of somewhat greater stature, 

 again a shift toward the mean of the type. 



