SOCIAL AND WORLD ASPECTS 205 



Differentiation of types is one measure of civilisation, 

 and no high type of culture could long be maintained 

 without it. The miner and the professor, the peasant 

 and the banker, each in his sphere makes his contri- 

 bution to civilisation, and so widens its boundaries 

 and increases the richness (mentally and morally, as 

 w^ell as economically) of the social inheritance of 

 tradition which makes the maintenance of culture 

 possible and the development of culture cumulative. 



Nevertheless, there is great need for improvement 

 in the general mental and ph3^sical level of our race 

 through some form of selection. Probabl}" no race 

 has ever rivalled the Greeks in the number of great 

 men they produced in a relatively small population 

 during a period of a few centuries. It should be 

 possible to devise some more effective means of 

 discovering the youths of exceptional quality in 

 every stratum of societ}', and giving them larger 

 opportunities of self-expression. Mere advocacy of 

 an indiscriminately higher birth-rate, fostered by 

 artificial doles to the poorer classes of society, \wi\\ 

 only achieve a dysgenic result. An able discussion 

 of these problems is to be found in Bateson's presi- 

 dential address to the British Association in Sydney, 

 Australia, 1914. 



The presence of various pairs of alternative 

 characters in the same individual probably has the 

 same stimulating effect in man that it has been 

 experimentally shown to have in such organisms as 

 maize and wheat. The frequently increased vigour 

 of hybrids was known to Darwin and other early 

 writers, but modern genetic experiments have given 

 the facts a much more precise orientation, although 

 its cause cannot yet be said to be fully understood. 

 The phenomenal growth of certain hybrid walnuts, 

 and the remarkable hardiness and vigour of such 

 hybrid trees as the London plane, are well known. 



