103 



to be the most sensitive. It is, also, noteworthy 

 that the West American trees are, on an 

 average, more rapid in growth than their East 

 American kindred, and attain higher and stouter 

 dimensions than the latter. As regards the 

 cultivation of the West American kinds in East 

 America only the coast territories and wooded 

 mountain valleys were taken into consideration, 

 while in West America the East American 

 species of trees thrive in the same way as the 

 European. The planting of European varieties 

 in East America is only likely to promise success 

 in the British section that is, in Canada but 

 this would be quite superfluous, as the closely 

 related varieties in those parts already fulfil 

 their purpose. 



For the afforestation of bare tracts of land it 

 is only the East American species that can be 

 considered. According to Professor Mayr's 

 estimate, the prairie should be suitable for forest 

 cultivation as far as 90 W. lat., but afforestation 

 with the usual far-reaching methods of planting 

 on extensive areas, which is unnatural, is not, 

 however, to be recommended. Let large areas 

 be planted with groups of trees in order to con- 

 tinue afforestation round each until the extended 

 groups close up together. This is also the 

 method which helps forward the natural distri- 

 bution of any species of wood. 



