484 TRANSMISSION 



SECTION V REGRESSION. IN GENERAL, THE OFF- 

 SPRING IS MORE MEDIOCRE THAN THE PARENTS; 

 THAT IS, WHATEVER THE PARENTAGE, THE OFF- 

 SPRING EXHIBITS A STRONG TENDENCY TO 

 REGRESS TOWARD THE MEAN OF THE RACE 



A glance at any regression table shows an uneven distribu- 

 tion of the population, with the largest numbers near the middle 

 of the table, exhibiting a strong tendency to cluster about the 

 center. Not only is this so, but if arty parental row (c to m) be 

 carefully studied, the following points will be noted : 



1. The mean or average heights of the children (column 18) 

 are in no case the same as the heights of the parents. Compare 

 column 1 8 with column i. 



2. When the parental height is above the mean of the race, 

 that is to say 68.5 inches and upward (c to g), then the mean 

 height of the children is something less than the height of the 

 parent (see any row from c to g). 



3. But when the parental height is below the mean of the 

 race, 67.5 inches and less (h to m), then the mean of the 

 children is greater than the height of the parent (see any row 

 from h to m). 



To illustrate : in row e are recorded the heights of the 68 

 children of 22 mid-parents 70.5 inches high. In column 18 we 

 see that the mean height of these 68 children was 69.5 inches, 

 or a height one inch beloiv the parentage, and by that much 

 nearer the general mean of the race. Again, in row k are 

 recorded the various heights of the 66 children of 1 2 mid-parents 

 65.5 inches tall. In column 18 we see that the mean or average 

 height of these 66 children was not 65.5 inches, as in the case 

 of the parents, but 66.8 inches, or 1.3 inches greater, and by that 

 much nearer the general mean of the race than were the heights 

 of their parents. 



This principle of regression, or, as it is sometimes called, the 

 "drag of the race," represents the "pull" of the ancestors 

 beyond the immediate parents. By this we see that, on the 

 whole, offspring are less exceptional than their parents ; or, 



