106 



iiot rcquiie the same external protection. It is like the genial 

 warmth of the seed-bed, or the nursery ; but where there is 

 freedom for the roots to expand without interruption, and 

 for the leaves to prepare the sap, without being vexed by the 

 winds. In fact, so extraordinary is the difference between 

 trees of the same species, placed in the one situation, and 

 in the other, that there is no visible point of resemblance 

 between them, excepting the leaves. We may, however, 

 perceive, that, as soon as the tops gain the summit of the 

 wood, their branches are shortened towards that quarter, and 

 both branches and spray are more thickly, though less vigor- 

 ously thrown out, in order to supply a defence against the 

 storm. Further, we find, that the outside rows, partaking 

 in some measure of the situation of trees in exposures, ob- 

 tain, in a proportional degree, the provisions adapted to such 

 a situation, and by consequence, a corresponding conforma- 

 tion and external character. 



It is a very curious fact, which has been verified by expe- 

 riment, and is worthy the attention of the scientific planter, 

 that these several properties or provisions, though once deter- 

 minately acquired, are not fixed or permanent in trees. The 

 vigilance of nature, if I may so speak, in adapting them to 

 every vicissitude of external circumstances, is so conspicuous, 

 as to dispose them gradually to divest themselves of the 

 properties adapted to one situation, when they happen to be 

 transferred to another, to which the opposite properties are 

 more congenial. For this reason, if a tree of some size, 

 which, in consequence of exposure, has acquired all the 

 properties already noticed, as adapted to that situation, be 

 transferred to the interior of the wood, it will, in a few years, 

 lay aside those properties, and assume all the others which 

 have been described, as peculiarly adapted to its new circum- 

 stances.* Thus, the law of nature seems to be, that shelter 



* Note VIII. 



