194 NATURAL INHERITANCE. [chap. 



collected specially, as no suitable material for the purpose 

 was, so far as I know, in existence. This was done by 

 means of an offer of prizes some years since, that placed 

 in my hands a collection of about 160 useful Family 

 Records. These furnished an adequate though only 

 just an adequate supply of the required data. In order 

 to show the degree of dependence that might be placed 

 on them they were subjected to various analyses, and 

 the result proved to be even more satisfactory than 

 might have been fairly hoped for. Moreover the errors 

 in the Records probably affect different generations in 

 the same way, and would thus be eliminated from the 

 comparative results. 



As soon as the character of the problem of Filial descent 

 had become well understood, it was seen that a general 

 equation of the same form as that by which it was 

 expressed, also expressed the connection between Kins- 

 men in every degree. The unexpected law of universal 

 Regression became a theoretical necessity, and on 

 appealing to fact its existence was found to be con- 

 spicuous. If the word " peculiarity " be used to signify 

 the difference between the amount of any faculty pos- 

 sessed by a man, and the average of that possessed 

 by the population at large, then the law of Regression 

 may be described as follows. Each peculiarity in a man 

 is shared by his kinsmen, but on the average in a less 

 deo-ree. It is reduced to a definite fraction of its 

 amount, quite independently of what its amount might 

 be. The fraction differs in different orders of kinship, 

 becoming smaller as they are more remote. When the 



