186 HEREDITY IN RELATION TO EUGENICS 



Fig. 166, — Rows of maize, each from a single ear of corn. The central 

 row (labeled) is from a 16 row-to-ear race self-fertilized for five years. Row to 

 left of center, self-fertilization prevented for six successive years. Row to 

 right, a first cross between long self-fertilized strains. 



clear that, while in certain strains consanguineous marriage 

 may not lead to defective offspring, in most families it will, 

 at least after a few generations. This is well illustrated in 

 corn-breeding where self-fertilization leads to rapid loss of 

 productivity and vegetative vigor (Figs. 166, 167). 



Let us now consider some of the statistical results gained 

 from a study of consanguineous marriages in a large popula- 

 tion. In 1858 Dr. Bemiss reported to the American Medical 

 Association on a collection of 833 consanguineous marriages 

 producing 3,942 children or an average of 4.6 children per 

 marriage. Of these children 28.7 per cent are said to be de- 

 fective, 3.6 per cent are deaf mutes, 2.1 per cent blind, 7 per 

 cent idiots, 1 per cent insane, 1.5 per cent epileptic, 2.4 per 

 cent deformed, 7.6 per cent ''scrofulous'' (i. e., probably 



