464 POPULAR SCIENCE MONTHLY. 



the law. Everything is on the side, physically speaking, of the 

 native. He has been acclimated, developing peculiarities proper 

 to his surroundings. He is free from the costly work of trans- 

 porting helpless women and children. The immense majority of 

 his fellows are like him in habits, tastes, and circumstances. The 

 invader, if he remains at all, dilutes his blood by half as soon as 

 he marries', and settles, with the prospect that it will be quartered 

 in the next generation. He can not exterminate the vanquished 

 as savages do, even if he would. Nay, more, it is not to his ad- 

 vantage to do so, for labor is too valuable to sacrifice in that way. 

 Self-interest triumphs over race hatred. He may kill off a score 

 or two of the leading men and call it exterminating a tribe, as 

 the great anthropologist Broca put it, but the probability is that 

 all the women and most of the men remain. In the subsequent 

 process of acclimatization, moreover, his ranks are decimated. 

 He struggles against the combined distrust of most of his neigh- 

 bors as well as with the migratory instinct which brought him 

 there in the first place. If he excels in intelligence, he may con- 

 tinue to rule, but his line is doomed to extinction unless kept 

 alive by constant re-enforcements. It has been well said that the 

 greatest obstacle to the spread of man is man. One of the objects 

 of our study will be to show, as Dr. Collignon aflirms, that " when 

 a race is well seated in a region, fixed to the soil by agriculture, 

 acclimatized by natural selection, and sufiiciently dense, it opposes 

 an enormous resistance to absorption by newcomers, whoever 

 they may be." 



Population being thus persistent by reason of its indestructi- 

 bility, a peculiar province of our study will be to show the rela- 

 tion which has arisen between the geography of a country and 

 the character of its people. Historians have not failed in the 

 past to point out the ways in which the migrations and conquests 

 of nations have been determined by mountain chains and rivers. 

 They have too often been content merely to show that the imme- 

 diate direction of the movement has been dependent upon topo- 

 graphical features. We endeavor to go a step further in indicat- 

 ing the manner in which the ethnic character of the population 

 has been determined by its environment, entirely apart from 

 political or historical events as such, and as a result of social 

 forces which are still at work. Thus we shall show that the 

 physical character of the population often changes at the line 

 which divides the hills from the plains. The national boundary 

 may run along the crest of the mountain chain, while the ethnic 

 lines skirt its base where the economic character of the country 

 changes. In other cases, the racial may be equally far from the 

 political boundary, since the river bed may delimit the state, while 

 the racial divisions follow the watershed. 



