172 PHYSIOGNOMY OF PLANTS. 



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 secre- 

 tion out of which new elementary organs are constructed 

 either of woody or cellular tissue, continues, without refe- 

 rence 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 vegeta- 

 tion 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 Pata- 

 gonia 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 (depen- 

 dent 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 



