40 On the Connexion behoccn the Leaves 



from local causes, are principally dependent on the foliage. 

 Even the diversity of the seasons, between one year and an- 

 other, gives rise to noticeable alterations in the qualities of the 

 produce from the same trees. 



Perhaps a further advancement in the knowledge of vege- 

 table nature may enable the scientific gardener to govern the 

 foliage of his trees by artificial methods, so as to atlapt them 

 better to the vicissitudes of locality, and to the production of 

 the more desirable fruits *. It is likely that the unfavourable 

 change induced upon the Downton pippin by a milder locality 

 than tliat of its native place, may depend upon a more luxu- 

 riant production of leaves ; and, if so, imder such new situa- 

 tions, the good qualities of that fruit might be again restored by 

 reduciuo- its exuberant foliage. The gradual deteriorations 

 arising from old age in trees, are equally evinced upon the 

 tbliage and the fruit. It belongs to the peculiar habits of some 

 varieties of trees and plants, to produce a greater or less pro- 

 portion of leaves than ordinary; and, perhaps, the particu- 

 larities in their physical properties make some of such leaves 

 more efficient than others; since the differences in their firm- 

 ness, thickness, and colour, may be reasonably supposed to 

 influence one or more of their vital offices. A remarkable in- 

 stance of the adaptation of foliage occurs in Winter Spinage, 

 the leaves being of a more dense texture, of a deeper colour, 

 and more compacted about the stems and roots, than in the 

 summer variety f. These and similar evidences may probably 

 indicate the hardiness of other esculent or ornamental plants, 

 and may lead to the introduction of many new, useful, or or- 

 namental vegetables, where they are at present unknown. In 

 the spring of 1815, the first tender leaves, and the immature 

 male catkins of the generality of our walnut-trees, were de- 

 stroyed by the frosts ; the subsequent crop was very few in 

 number, and of indifferent quality. I consider those conse- 

 quences to have arisen from the destruction of the first shoot 

 of leaves : but there was also in the same season an unusual 

 number of abortive or empty nuts, and this was apprehended 

 to be wholly owing to the want of masculine mipregnation, as 



* I am informed by a practical gardener, that buds may be artificially 

 produced upon the long naked spaces of boughs, by making scars into the 

 bark, similar to those left by imperfect leaves, or gem-like stipula;. Indeed, 

 nature points out the efficacy of such methods, by those clusters of twigs so 

 often displayed in the branches of the elm, birch, and wild cherry, and which 

 result froni the punctures of insects. 



f The attenuated and delicate foliage of forced hardy plants and housed 

 »hrul)s, is known to be more readily injured by frost than if they had re- 

 mained exposed; and the physical differences in the texture of such leaves 

 sufficiently explain the cause of that acquired tenderness. 



I have 



