LIMITATIONS OF EUGENICS 307 



sesses. We could not, for example, breed a human race with 

 wings, however desirable such a characteristic might seem. 

 We are limited definitely for all time to the hand type of 

 appendage. But there are different types and sizes of hands 

 among human beings among which a selection might be nuide 

 if this were considered desirable, as for example normal 

 hands, short-firigered hands (i. e,, brachydactyl), hands with 

 a reduced number of fingers {i. e., syndactyl), and hands with 

 an increased number of fingers {i. e., polydactyl). These 

 several types of hand are known to be hereditary. If the 

 unusual types were superior to the normal, we might through 

 heredity make them replace the normal in the race. But in 

 reality, the normal type of hand seems on the w^hole to be 

 the best type, and so we have no desire to change it. The 

 same is true as regards most human traits known to be in- 

 herited, whether physical or intellectual. Our ideal is in 

 I general the normal. There are certain types of abnormality 

 which we should be glad to see become less frequent in occur- 

 rence, as for example albinism, night blindness, color-blind- 

 ness, and haemophilia. A complete control of heredity would 

 render their elimination from the race possible, but it is 

 doubtful if they are serious enough to call for such elmiina- 

 tion, even if human matings w^ere wholly controllable by a 

 single central agency, which of course they are not. For in 

 discriminating against persons possessing such minor defects 

 as these we should be in danger of rejecting some of our 

 human stock which is best in regard to characteristics of 

 much greater consequence. The independent inheritance of 

 traits must ever be kept in mind in deciding who are desir- 

 able and who undesirable parents, weakness in one particular 

 being frequently offset by unusual strength in another. Those 

 undesirable traits which are inherited in the simplest way, 

 as Mendelian characters, are not likely to become very com- 

 mon in a freely intermarrying population. It is only when 

 society becomes stratified, and class distinctions arise with 

 castes or families closely intermarrying, that heredity is likely 

 to bring Mendelian recessive defects repeatedly to the sur- 



