HUMAN LIFE 



tion of three-fourths spinning yellow and 

 one-fourth spinning white I say if I 

 can tell a silk grower these things as 

 facts which he can rely on and I can 

 actually do this as a result of my own 

 experiments and observations he will 

 find them not only interesting but useful. 

 Think what such knowledge of heredity 

 means to the plant and animal breeder. 

 And then think of what similar knowledge 

 concerning the inheritance of human 

 traits may mean in human life. 



The example I have given of the hered- 

 ity behavior of a certain silkworm charac- 

 teristic is a case of typical Mendelian 

 inheritance. The inheritance of blue or 

 brown eyes in men follows the same 

 course; so does six and five-fingeredness; 

 so does a certain form of color blindness 

 paired with color visualness; so does 

 Huntington's chorea paired with freedom 

 from this fatal infirmity; so does, although 

 in less perfect form, feeble-mindedness 

 paired with full-mindedness. Mendelian 

 inheritance is the order or behavior of the 

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