viii] HEREDITY 103 



occurrence of apparently continuous variation within 

 a discontinuous category is clearly shown. Of other 

 Mendelian characters in man, colour-blindness, com- 

 plicated by its relation with sex, has already been 



Fig. 12. Brachydactylous hands. (From Bateson, after Farabee.) 



mentioned. Several cases are known in which an 

 abnormality behaves as a simple dominant, e.g. the 

 condition of the fingers known as ' brachydactyly,' in 



