Heilprin.] -'■O [Jan. 15, 



In the north temperate regions the timber line, where marked by the 

 disappearance of conifers at all, seems to characterize indiscriminately 

 the zone either of pines or firs (spruces); probably in the greater number 

 of instances the latter are the most far-reaching trees. In the Harz 

 mountains, the Riesengcbirge, the Bohmerwald, the Jura mountains, and 

 in many parts of the Alps, Carpathians and Pyrenees the firs are the 

 delimiting zone of forest ; but again, in other parts of the Alps and Pyre- 

 nees, in the Tatra (Central Carpathians), the Altai, and on many of the 

 mountain crests of the Mediterranean region, the pines (notably Finns 

 cembra) considerably overtop the firs, even if they do not form that dis- 

 tinct vegetal zone which is constituted by the latter. In North America, 

 perhaps even more than in Eurasia, do the firs constitute the upper- 

 most coniferal zone, a zone which is so eminently defined on the higher 

 elevations (f the Appalachian system of mountains (White mountains, 

 Black mountains of North Carolina). In the Rocky mountains the pines 

 and firs both attain the timber line, but the latter predominate by far as a 

 zone-making element ; indeed, on many of the more elevated summits 

 the pines only sporadically mingle in with firs. It is the more interesting, 

 therefore, to find that on the still higher summits of Mexico the reverse 

 order obtains. The zone of firs (consisting of Abies religiosa), as I had 

 occasion to observe on Orizaba, Popocatepetl, Txtaccihuatl and theNevado 

 de Toluca, virtually ceases at about 11,500-13,000 feet,* or two thousand 



and 15,91t feet, or nearly 150 feet higher than the Saxifracja BoussingaicUi, from the slopes 

 of Chimborazo,which Humboldt considered to be "the highest growing phanerogamic 

 plant in the world" ("Views of Nature," p. 234). Again, Humboldt himself observed 

 occasional specimens of tree-like Verbesina on Pichincha at an elevation of nearly 14,400 

 feet (" Kleiuere Schriften," p. 57). It seems likely that the measurements of altitude in 

 both of these cases are given too high a value ; at any rate, the more recent surveys of the 

 Andean summits have, in nearly all cases, tended to diminish rather than to increase 

 the formerly accepted measurements. Raimondy reports Sambucus Peruviana and 

 PolylepU racemosa from an elevation of 14,390 feet on the Peruvian Andes ; Polylepis 

 tomenfcUa was observed by Weddell at 14,710 feet, and P. lanuginosa, hy Jameson, on 

 Chimborazo, at 13,965 feet. Most of these upper trees are dwarfed, scarcely attaining 

 more than a few feet in height, and, indeed, the actual timber line falls considerably 

 below the elevations here given. Humboldt makes the interesting observation that in 

 the region about Quito trees 45-CO feet in height are rarely met with above some 8800 

 feet. At Chicla, on the Peruvian Andes (13° degrees south of the Equator), at an eleva- 

 tion of 12,200 feet. Ball observed but a single tree, Sajiibucus Peruviana, a form closely 

 related to the common black elder of Europe (" Notesof a Naturalist in South America," 

 p. 101, 18S7). In remarkable contrast to these cases of special elevation is the condition 

 of the forest vegetation on Kilima 'Njaro, on approximately the third degree of south 

 latitude. According to Dr. Hans Meyer, the "average limit of the forest belt is about 

 9500, the extreme limit imposed by tlie climatic conditions being some six or seven hun- 

 dred feet higher" ("Across East African Glaciers," p. 132, 1891); phanerogamic plants are, 

 however, found on the same mountain up to 15,420 feet {op cit., p. 167). In the Sunda 

 islands Uava, Sumatra, Borneo), which lie almost under the Equator, as is well known, 

 the timber Ime also fiills below 10,000 feet, although individual mountain summits rise 

 2000 and 3500 feet higher. 



* We met with the last spruces on Ixtaccilniatl at approximately H.^OO feet; the 

 lowest were found at about 9200 feet, or very nearly 1000 feet lower than we observed 

 them on the peak of Orizaba. I have no doubt that the species in question is found at 



