G ALTON'S LAW 



325 



Fig. 29. — Diagram illustrating Galton's Law of Ancestral Inheritance. 

 (After Gal ton.) The figure was originally due to Mr, A. J. Meston 

 {The HoYseman, Chicago, Dec. 28, 1897). 



" The area of the square diagram represents the total heritage of any particular form or 

 faculty that is bequeathed to any particular individual. It is divided into subsidiary squares, 

 each bearing distinctive numbers, which severally refer to different ancestors. The size of 

 these subsidiary squares shows the average proportion of the total heritage derived from the 

 corresponding ancestors. . . . The subject of the pedigree may be called i. Thenceforward 

 whatever be the distinctive number of an ancestor, which we will call w, the number of its 

 sire is 2», and that of its dam is zn-\-\. All male numbers in the pedigree are therefore even 

 and all female numbers are odd. To take an example — 2 is the sire of i, and 3 is the dam 

 of I ; 6 is the sire of 3 and 7 is the dam of 3. Or, working backwards, 14 is a male who is 

 mated to 15 ; their offspiing is 7, a female, who is mated to 6 ; their offspring is 3, a female, 

 who is mated to 2, and their offspring is i, the subject. . . . The numbered squares could 

 be continued indefinitely ; in this small diagram they cease with the fourth generation, 

 which contributes a i6th part of the total heritage, therefore the whole of the more distant 

 ancestry, comprised in the blank column, contributes one-sixteentli also " (Gallon, 1898). 



