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Show ANNOTATIONS AND ADDITIONS. 343 attention of vegetable physiologists, and appears to be of only very rare occurrence in other dicotyledonous trees. The remaining stumps of White Pines which have been cut down continue for several years to make fresh layers of wood, and to increase in thickness without putting forth new shoots, leaves, or branches. Gop pert believes that this only takes place by means of root nourishment received by the stump from a neighboring living tree of the same species; the roots of the living individual, which has branches and leaves, having become organically united with those of the cut tree by their having grown together. (Goppert, Beobachtungen iiber das sogenannte Umwallen der Tannen-stOcke, 1842, s. 12.) Kunth, in his excellent new "Lehrbuch der Botanik," objects to this explanation of a phenomenon which was known, imperfectly, so early as Theophrastus. (Hist. Plant. lib. iii. cap. 7, pp. 59 and 60, Schneider.) He considers the case to be analogous to what takes place when metal-plates, nails, carved letters, and even the antlers of stags, become enclosed in the wood of a growing tree. "The cambium, i. e. the viscid secretion out of which new elementary organs are constructed either of woody or cellular tissue, continues, without reference to the buds (and quite apart from them), to deposit new layers of wood on the outermost layer of the ligneous substance." (Th. i. s. 143 and 166.) The relations which have been alluded to, between elevation above the level of the sea and geographical and thermal latitude, manifest themselves often when we compare the tree vegetation of the tropical part of the chain of the Andes with the vegetation of the north-west coast of America, or with that of the shores of the Canadian Lakes. Darwin and Claude Gay have made the same remark in the Southern Hemisphere, in advancing from the high plains of Chili to Eastern Patagonia and Tierra del Fuego, where they found Drymis winteri and forests of Fagus antarctica and Fagus forsteri forming a uniform covering throughout long, continuous lines, running from north to south, and descending to the low grounds. We find even in Europe small deviations (dependent on local causes which have not yet bean sufficiently examined) from the law of constant ratio as regards stations or habitat of plants between elevation above the sea and geographical latitude. I would recall the limits, in respect to eleva- |
