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useful forester. Harriet said she would tell all 

 her boy and girl friends what she knew of this 

 squirrel's tree-planting ways, and would ask her 

 uncle not to shoot the little tree-planter. 



As we followed the trail up through the woods, 

 I told Harriet many things concerning the trees, 

 and the forces which influenced their distribu- 

 tion and growth. While we were traveling west- 

 ward in the bottom of a gulch, I pointed out to 

 her that the trees on the mountain that rose on 

 the right and sloped toward the south were of a 

 different kind from those on the mountain-side 

 which rose on our left and sloped toward the 

 north. After traveling four miles and climbing 

 up two thousand feet above our starting-place, 

 and, after from time to time coming to and pass- 

 ing kinds of trees which did not grow lower down 

 the slopes, we at last came to timber-line, above 

 which trees did not grow at all. 



In North America between timber-line on the 

 Rockies, at an altitude of about eleven thousand 

 feet, and sea-level on the Florida coast, there are 

 about six hundred and twenty kinds of trees and 

 shrubs growing. Each kind usually grows in the 



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