456 ELEMENTARY BIOLOGY 



The application of our knowledge of heredity to human affairs will 

 probably be along the line of showing us what types of marriages are 

 likely to produce offspring that are undesirable in one way or another. 

 We already know that certain abnormalities of physical structure or 

 of mentality are transmitted in a definite way, and we are therefore 

 warranted in counseling men and women who belong to families that 

 show these characters not to marry others of similar stock. In the 

 course of time we shall no doubt develop certain standards of fit- 

 ness for marriage which will be enforced largely by the same kind 

 of public opinion and tradition as now distinguishes the customs of 

 different peoples. 



