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a limited scale, but this unintentionally; -whereas 

 with man it is the work of design, and ever increasing 

 with his requirements. In like manner he extirpates, 

 disseminates, and domesticates animals, destroying 

 those that are noxious and hostile, carrying from one 

 region to another those that are useful (and occasion- 

 ally by accident some that are injurious), and domesti- 

 cating and increasing in a wonderful manner those on 

 whom he relies for his food, clothing, and assistance 

 in his daily labours. Indeed, wherever man settles 

 down he becomes a modifier of nature, and as one 

 portion of nature is intimately associated with every 

 other portion, so every modification ramifies and 

 extends far beyond the circle of direct interference. 

 The feUing of forests and the drainage of land, for 

 example, afi'ect climate, and with the slightest change 

 in climate arises a whole round of alteration in plants, 

 and consequently also in the animals that subsist 

 upon them. The extirpation of certain plants may 

 lead to the destruction or removal of certain animals, 

 and with the destruction of these animals others may 

 so increase as to effect the destruction of a second set 

 of plants, thus involving the extinction or removal of 

 a third set of animals, and so on through, interminable 

 ramifications. In this way man has materially inter- 

 fered with the distribution of plants and animals, and 

 this more especially since the white man of Europe 



