182 PEINCIPLES OF STOCK-BREEDING. 



merit may not by this system be established as a per- 

 manent variety. 



" It is therefore evident that consanguinity alone 

 cannot be accepted as the cause of deaf-mutism, nor 

 consequently as the sole cause of any other diseases or 

 defects which have from time to time been ascribed to 

 it." ' 



In 1858, Dr. Bemis, of Kentucky, made a report a 

 to the American Medical Association on " Marriages 

 of Consanguinity," in which he gives an imperfect 

 history of eight hundred and seventy-three instances 

 of such marriages. 



The conclusions of the author are briefly stated in 

 the paper as follows : " I feel satisfied, however, that 

 my researches give me authority to assume that over 

 ten per cent, of the deaf and dumb, and over five per 

 cent, of the blind, and near fifteen per cent, of the 

 idiotic in our State institutions for subjects of those 

 defects, and throughout the country at large, are the 

 offspring of kindred parents, or of parents -themselves 

 the descendants of blood intermarriage." 



It will be observed that Dr. Bemis does not assume 

 that the relationship of the parents is the cause of the 

 defects of their children, and there is nothing in the 

 report to warrant such a conclusion. The facts pre- 

 sented in the report are of particular interest, as they 

 furnish a good illustration of the difficulty of obtain- 

 ing exact statistical information on subjects of this 

 kind. One source of fallacy, arising from the manner 



1 British and Foreign Medico- Chirurgical Review, July, 1863, pp. 

 179, 180. 



8 " Transactions of the American Medical Association," vol. ii., p. 319. 



