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 thick- 

 ness, without putting forth new shoots, leaves, or branches. Goppert 

 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 expla- 

 nation 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 cam- 

 bium, 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. t. 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 uni- 

 form covering throughout long, continuous lines, running from north 

 to south, and descending to the low grounds. We find even in Eu- 

 rope small deviations (dependent on local causes which have -not yet 

 been 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 oleva- 



