CHAPTER VIII 



CAMP-FOLLOWERS OF COMMERCE, OR 

 ANIMALS INTRODUCED UNAWARES 



Brought from under every star 

 Blown from over every main. 



We sail'd wherever ship could sail, 

 We founded many a mighty state. 



TENNYSON. 



SINCE nomadic man first began to move his tents from 

 one fertile valley to the next, he has taken his place with the 

 beasts of the field and the fowls of the air as an unconscious 

 factor in the dispersal of living things. The effects of this 

 unintentional transference of plants and animals, limited by 

 the extent of human migrations, may in the earliest days of 

 our race have been of small moment; yet even in the Old 

 Stone Age they must already have had considerable signi- 

 ficance, for no fact is clearer than that succeeding periods of 

 climatic change in Europe brought with them from lands 

 unknown, their own characteristic peoples. 



We know that the people of the New Stone Age did 

 actually convey with them from western Asia, domestic 

 animals strange to the fauna of Europe, but what strange 

 bed-fellows and camp-followers accompanied them willy-nilly, 

 we can only guess. With modern extensions of travel and 

 commerce, and perfected means of intercommunication across 

 land and sea, the unintentional transference of plants and 

 animals has entered a new phase, and has already become 

 a matter of grave economic importance, which has demanded 

 and has received, in countries whose scientific eye is un- 

 dimmed, the attention of governments and of law-makers. 



Plants are less mobile than animals and therefore afford 

 a more striking illustration of the efficiency of man as an 

 agent of dispersal. When the little lonely island of St Helena, 

 lying in the middle of the Atlantic Ocean, 1000 miles from 



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