vii.] DISCUSSION OF THE DATA OF STATURE. 99 



the results in detail. They seem to show a Eegression 

 of about two-fifths, which differs from that of one-third 

 in the ratio of 6 to 5. This direct observation is so 

 inferior in value to the inferred result, that I disregard 

 it, and am satisfied to adopt the value given by the 

 latter, that is to say, of one-third, to express the 

 average Regression from either of the Parents to the 

 Son. 



b. Mid-Parental : The converse relation to that which 

 we have just discussed, namely the relation between 

 the unknown stature of the Mid-Parent and the known 

 Stature of the Son, is expressed by a fraction that is 

 very far from being the converse of two-thirds. Though 

 the Son deviates on the average from P only f- as 

 widely as his Mid-parent, it does not in the least follow 

 that the Mid-parent should deviate on the average from 

 P, |- or 1-^, as widely as the Son. The Mid-Parent is 

 not likely to be more exceptional than the son, but 

 quite the contrary. The number of individuals who 

 are nearly mediocre is so preponderant, that an ex- 

 ceptional man is more frequently found to be the 

 exceptional son of mediocre parents than the average 

 son of very exceptional parents. This is clearly shown 

 by Table 11, where the very same observations which give 

 the average value of Filial Regression when it is read 

 in one way, gives that of the Mid-Parental Regression 

 when it is read in another way, namely down the vertical 

 columns, instead of along the horizontal lines. It then 

 shows that the Mid-Parent of a man deviates on the 



H 2 



