IX 



TREES THAT TRAVEL 



BEFORE the modern era of steam and elec- 

 tricity the history of man was largely a his- 

 tory of his migrations. When his house stood still, 

 he stood still mentally and physically. When he 

 moved about, his mind grew and his body changed 

 its colour and its conformation. 



The same is true of the trees. When they are 

 content to stay quietly at home, they go on repro- 

 ducing themselves in the same old way for end- 

 less generations. As soon as individuals or even 

 extensive groups among them decide to travel a 

 bit they undergo marvellous changes in the lands 

 of their adoption. The tiny dogwood, scarcely 

 six inches tall in Alaska, becomes a sixty-foot giant 

 in Texas and Florida. In the far North the honey 

 locust is little more than a shrub. On reaching the 

 southern United States or Mexico it becomes a 

 medium-sized tree, wonderfully defended by thorns 

 and prickles. In the still more luxurious climate 



of South America it develops into an immense struc- 



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