IX. ALTITUDE. 463 



by step as the land rises in any mountain region the 

 vegetation assumes, more and more, a polar character ; 

 and in the mountains of the tropics, a succession of 

 stages have been distinguished, corresponding in the 

 general peculiarities of the plants which clothe them, to 

 tracts extending horizontally, in succession, on the sea- 

 level, from the base of these mountains to the frozen 

 regions within the arctic and antarctic circles." 



In these passages, and others which succeed them, 

 there are just those few grains of truth among the chaffy 

 falseness, which must forbid a denial in toto. Increased 

 severity of climate on the mountains does not act on the 

 flora " exactly in the same way " as the colder climate of 

 regions farther from the equator. And it would assuredly 

 puzzle the writer of those vaguely general jjassages, if he 

 were called upon to enumerate the arctic and antarctic 

 floras, species by species, or even genus by genus, re- 

 peated near the snow-line on tropical mountains, — or, 

 conversely, to find the plants of the tropical mountains 

 among those brought home by our arctic voyagers. 



The correction here sought to be impressed, is, that in 

 receding from polar towards equatorial latitudes, the alpine 

 or mountain floras themselves really become less and less 

 ai'ctic ; although it may be quite true that the change is 

 less rapid and complete, than that observed between the 

 floras of the plains, if severed as widely in latitude. In a 

 southerly direction, i^olar and arctic species successively 

 cease to be seen even upon the highest mountains ; their 

 places being more numerously supplied by other non- 

 arctic species ; and these latter frequently having a closer 

 generic and ordinal alliance with the comparatively 

 southern species of the low grounds. It is important to 

 note this fact, in reference to certain h3q5othetical views 

 of floral distribution lately promulgated. And it may 



