i62 HEREDITY AND EUGENICS 



downwards, and produce nothing but degeneracy. 

 The rapid multiphcation of these people is most 

 serious. Miss Ke}^ points out that pubhc opinion is 

 helpless to prevent marriages between them, and 

 suggests State control of marriages through a State 

 Eugenics Board, with power to prohibit certain 

 unions under penalty after studying the hereditar}' 

 defects of the proposed parties to a marriage. But 

 it is not to be expected that a ban on marriage would 

 prevent people of this type from reproducing them- 

 selves. It is noticeable that while defective members 

 of these stocks remain for the most part within a 

 few miles of their place of origin, and hence tend to 

 establish a defective group in the community, the 

 better members, by marriage or otherwise, remove to 

 greater distances and a new^ environment. 



Various attempts to analyse temperaments and 

 their inheritance have been made, notabl}^ by 

 Davenport (191 5). He divides temperaments into 

 h3^perkinetic or nervous and hypokinetic or phleg- 

 matic, and recognises tw^o grades of each. A dualism 

 of this kind, romantic and classic types, radical and 

 conservative, feebly and strongly inhibited, he finds 

 running through the whole population ; also a tendency 

 for matings to take place between unhke tempera- 

 ments. He hypothecates a factor E producing 

 periodic excitement, its absence e producing calmness. 

 Another factor C makes for cheerfulness, while c 

 permits more or less periodic depression ; and he finds 

 that C and E are independently inherited. As a 

 modern attempt in the anatomy of melancholy, this 

 shows courage in the effort to explore a field which 

 is notoriously full of pitfalls. That it is inadequate 

 as a complete analysis appears obvious. The desira- 

 bility of creating '' factors " for calmness and cheer- 

 fulness appears very doubtful. 



Nomadism, or the wandering instinct, Davenport 



