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NOTICES OF AUTHORS. 



power of ripening seed is not increased by shelter in 

 proportion to the power of groT\dng — perhaps not 

 at all ; we instance the Spanish chestnut, vvhich 

 has scarcely ever been kno^^^^i to ripen seed in Scot- 

 land. Seed-grown trees will, therefore, under Na- 

 tui'e's arrangement, not be found extending much 

 beyond the line of seed ripening. From nuts, 

 acorns, and other seeds, fully developed, being found 

 in elevated mosses in this country, other causes than 

 shelter appear to have existed. 



Before this country was so much overrun by men 

 and oxen, a great deal of timber had existed, cover- 

 ing much of the superior land which is now under 

 tillage. This consisted chiefly of the oak, Scots fir, 

 birch, hazel, and alder, — the oak extending north - 

 ward and to elevations, and ripening seed, and at- 

 taining to a size which it does not now do, either 

 wild or cultivated, in the same latitude, neither here 

 nor in any other portion of the world ; which, along 

 with some other facts, lead to the supposition, that 

 the climate has changed a little, — in part, possibly, 

 as we have before stated, from the gradual formation 

 of peat, to which, overthrown oak forest, from the 

 abundance of the tannin principle, has a great dis- 

 posing influence, even under a warmer climate than 

 present Scotland. The highest latitude to which a 

 tree, or any other kind of plant, reproducing by seed. 



