584 MIGRATIONS OF RACES OF MEN CONSIDERED HISTORICALLY. 



influence may have been upou him in causing tribes to move from place 

 to place, and in bringing about alterations of racial types. 



The geological record supplies ample evidence how greatly the si)ecies 

 of animals and plants have transferred themselves from one dwelling 

 place to another in distant ages. The horse, in his earlier forms, was 

 abundant in America, but he vanished there, and had been long extinct 

 when the Spaniards of Oortez won JNIexico by the terror he inspired. 

 The camel, it appears, was originally a New World beast, and the 

 gigantic ^eg((ow<, of California, a European tree. But it is seldom that 

 we are able to fix the causes which have brought about these transfer- 

 ences. And even with regard to those Citmparativelj' few migrations of 

 animals which haveoccurred within recent times it is seldom that any pal- 

 pably operative ground canbeassigued. The latest instance of any con- 

 siderable migration, apart, of course, from theagency of man, is theinva- 

 sion of Europe by the brown rat, a native, it seems, of East Central 

 Asia, which has practically expelled the black rat from Europe, just as 

 the latter has been ejecting weaker rodents from South America. 



In prehistoric times the movements of animals must have frequently 

 told upon man. It appears that some centuries before our colonists 

 entered North America the bufialo had begun to move eastward from 

 the i)rairie highlands in and near the R')cky Mountains toward the 

 Mississippi ; and in order to tempt him still farther eastward the Indians 

 began to burn the forests which covered its banks and those of the 

 Ohio River in what are now the States of Illinois, Indiami, and Ken- 

 tucky. The abundance of animal food thus brought within their reach 

 seems to have checked the progress of the tribes in the arts of seden- 

 tary life, throwing them back into the stage of hunters. 



Since man, in his advancing civilization, has begun to domesticate 

 animals and to understand how to improve the soil and make full use of 

 Its capacities, the chief transfers of animals and plants to new regions 

 have been due to his action. He has peopled the New World and 

 Australasia with the horses, cattle, and sheep of Ihirope, turning to 

 account tracts which might otherwise have remained a wilderness. The 

 trees he has brought from distant regions have sometimes grown to for- 

 ests and changed the aspect of whole countries. Thus, the toi)S of the 

 Neilgherry hills in Southern India have nearly lost their beautiful 

 ancient woods, and are now, since the English took them in hand, cov- 

 ered with the somber Eucalyptus and Acacia mclanoxyloti from Austra- 

 lia, or with plantations of tea from China, or of quinine from Paraguay. 

 The landscape of Egypt, as we see it, must be quite different from that 

 which Moses or Herodotus saw; for most of the trees belong to si)ecies 

 which were then unknown on the Nile. JMany creatures and many 

 plants have also followed man without his will. The rats which our 

 ships carry, and the mosquitae-; whose eggs lurk in the water barrels, 

 hnd their way to land and plague new countries; the English sparrow 

 is now a nuisance in North America, though less pernicious than the 



