OCR Text |
Show 300 ACTION AND REPOSE which me_rely serves to protect the other parts from externa~ mterruption or injury. [By-the-way, the possessiOn of a protecting epidermis is one of t~e best popular means of distinction between orgamc and inorganic beings, in those obscure species in which they.resemble each other the most.] At the close of the season, the whole of the cambium, or changeable pulpy matter, is formed into wood and bark, which adhere firmly to each other at the line of separation; and when that is accomplished, the leaves are of no further use, and they change colour and fall off; for though there are vessels apparently of a woody texture in the leaves, they are not the product of the same action as the wood of the tree. That action extends only to the base of the petiole, or foot- stalk of the leaf, and as a pellicle of epidermis gradually forms upon that, as it becomes complete, the leaf separates without a wound. Whenever indeed the action of a tree ceases, whether naturally at the season when it passes into repose, or in consequence of an external check, such as transplanting it while in leaf, the last action of the tree-the effort of nature by which it preserves its vitality-is the formation of that epidermis between the twigs and the petioles of the leaves. If the tree succeeds completely in forming that, and the withered leaves fall off spontaneously, or can be removed by a touch, the tree may be considered as safe, though it may remain a long time before positive action again begins; but if the withered leaves remain firmly on the twigs, it is a sign that the tree is affected in its general action, and that it will "die down" in those parts to which the withered leaves adhere, if it does not perish altogether. When the action of the leaves ceases, that of the absorbing rootlets ceases also, because the matter which is taken in by them is not convertible into wood or bark without the co-operation of the leaves; IN TREES. 301 a~d if the leaves are stripped off, or eaten by caterpwars, or destroyed by any other means, the only effort th':t can be made by the food from the root, is the P':lshmg out of new leaves and buds; and if these are p1cked off as soon as they make their appearanc~,. no more wood is added to the tree. It is by avatlmg themselves of this property of trees that t~e people of China contrive to get several succesSIOns of leaves from their tea-plants in the course o~ the ~e ason. But as the first crop comes after the ~mter s repose of the tree, and when the roots are ~~ the greatest activity, that crop is fine and more ~Ighly flavoured than those that are gathered later )n the season. As in most trees the roots are put out before the ~tern at the commencement, in each year's action, the rootlets, or absorbent vessels of each year are form ed before the leaves of that year. For 'that reason, t~e autumn or winter is a much better season for plantm.g trees than the spring, provided those trer.s are mtended. to show leaves in the ensuing summer. Indeed, If the transplanting is delayed til1 ) ~he rootlets aTe .fully formed, the tree is in as much Jeopardy as If It were completely in leaf, or even m morB. The action of the rootlets ceases sooner than that ~f the leaves, so that they pass into the state of wmter repose at an earlier period of the autumn. During the first winter after it issues from the aco.rn, the oak o.f the first year, with the loss only of ~ts le.aves whiCh have been cast off, remains inactive till the return of the season. When that comes round, the elaboration of the second oak is begun. The. gro~th of that oak, though still an interesting opera~wn, Is _not quite so wonderful as the first, for there Is a basis of both wood and bark for the second one; and the vegetable action is expanded over the whole surface where theyc c oc me in con. tact·' wherea.s. , |