48 WINTER FIELD MEETING. 



formed for the next season's work from attaining perfec- 

 tion. It prevents the scar which is left from being 

 perfectly healed over; and, finally, it prevents the leaf 

 from becoming brightly colored, but instead, the frost 

 withers it at once. 



The leaf, left to finish up its work, commences at the 

 proper time as the season advances, to deposit at the base 

 of the leaf stem, a corky layer, which separates the leaf 

 from the ducts or tubes, which had previously connected 

 it with the living cells of the branches and trunk of the 

 tree, and thence with the roots. It is now that the 

 autumn sun ripens the materials deposited in the leaves, 

 and produces the beautiful tints which are the charm of 

 our Xew England autumn, and for which we are indebted 

 entirely to our own native trees ; those of foreign intro- 

 duction, being mostly but brown or dull-colored objects 

 at the season, when our native species are clothed in their 

 gorgeous raiment. 



As previously indicated, under different influences, the 

 same species of trees may not always present the two 

 phases, leafy and leafless, with which we are familiar. 

 An evolution has undoubtedly gone on in previous time, 

 and is still proceeding, by which evergreen trees have 

 become deciduous. There are some trees and shrubs 

 which possess an evergreen foliage in their natural habitat, 

 or rather in the region where they attain their greatest per- 

 fection, but which in a colder climate become deciduous. 

 This is the case with the Willow Oak (Quercus Phellos) 

 which at the south retains its foliage until the new growth 

 has commenced, while at Philadelphia it is regularly de- 

 ciduous in autumn. There are Honeysuckles of the same 

 habit under similar influences. Darwin speaks of the 

 Turkish Oak (Quercus cerris), which by its varieties 

 may be arranged as evergreen, sub-evergreen, and de- 



