94 NATURAL INHERITANCE. [CHAP. 



1'21 inch, which agrees excellently with the observed 

 value. 1 



Variability in Co- Fraternities. As all the Adult 

 Sons and Transmuted Daughters of the same Mid- 

 Parent, form what is called a Fraternity, so all the Adult 

 Sons and Transmuted Daughters of a group of Mid- 

 Parents who have the same Stature (reckoned to the 

 nearest inch) will be termed a Co-Fraternity. Each 

 line in Table 11 refers to a separate Co-Fraternity and 

 expresses the distribution of Stature among them. 

 There are three reasons why Co-Fraternals should be 

 more diverse among themselves than brothers. First, 

 because their Mid-Parents are not of identical height, 

 but may differ even as much as one inch. Secondly, 

 because their grandparents, great-grandparents, and so 

 on indefinitely backwards, may have differed widely. 

 Thirdly, because the nurture or rearing of Co-Fraternals 

 is more various than that of Fraternals. The brothers 

 in a Fraternity of townsfolk do not seem to differ more 

 among themselves than those in a Fraternity of country- 

 folk, but a mixture of Fraternities derived indiscrimi- 

 nately from the two sources, must show greater diversity 

 than either of them taken by themselves. The large 

 differences between town and country-folk, and those 

 between persons of different social classes, are con- 

 spicuous in the data contained in the Eeport of the 



1 In all my values referring to human stature, the second decimal is 

 rudely approximate. I am obliged to use it, because if I worked only to 

 tenths of an inch, sensible errors might creep in entirely owing to arith- 

 metical operations. 



