GEOGRAPHICAL ISOLATION 69 



his own skin, wherever he is able to find food and 

 shelter, he is at home. Modern man is bound to his 

 locality by a thousand chains, forged by his more 

 complex needs and emotions. In his case, more- 

 over, there exist causes of isolation other than those 

 found amongst animals. First there is language, 

 with all its implications of thought and feeling, 

 memories of past history, political and social ideals, 

 differences that act strongly against freedom of 

 intercourse, even where geographical barriers do 

 not exist. Still more effective in producing isolation 

 are the innumerable regulations, made for military 

 and fiscal regions, hedging the frontiers. All the 

 great nations, while they welcome the temporary 

 visitor, are beginning to scrutinize the alien immi- 

 grant more and more closely, some of them accept- 

 ing him only under severe conditions, all of them 

 looking on him with little favour. Even when the 

 frontiers are mere lines drawn on a map, indifferent 

 to physical or racial features, the nations stand back 

 to back, each facing its own capital, and in every 

 way add to the difficulties of intercourse and so 

 secure those conditions under which divergent modi- 

 fication is most rapid. 



As the environment in two areas cannot be identi- 

 cal, the mere fact of isolation, even if not absolute, 

 must lead to some divergent modification, but it also 

 provides the opportunity for different systems of 

 "Kultur" to produce their different effects on material 

 that was at first practically identical. It is plain 

 that the process may be of two kinds. It may 

 actually modify the stock, so that in course of time 

 the inborn qualities and capacities, all the charac- 



