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INFLUENCE OF CLIMATE ON PLANTS.* 
SOLAR HEAT. 
Could we have entertained a well-grounded opinion that popular desires are 
always guided by permanent advantage, and directed towards the emolument of 
science, we might have felt ourselves justified in multiplying these papers to an 
almost indefinite extent ; so comprehensive and transcendently important is the 
subject of which they treat. But, impressed with the conviction that, to the 
majority of our readers they must now be growing tedious ; and in accordance with 
the saying of one possessing deep penetration and knowledge of human nature, that 
" variety 's the spice of life ; " for we believe that this applies with no less force to 
literary and scientific recreation than to the meaner occurrences and engagements of 
general society ; we shall speedily close this series, by portraying some of the most 
striking effects on vegetation of the varied climate attendant on different zones, 
altitudes, and other circumstances which influence the temperature of a locality. 
On a mountain of sufiicient size and height within the tropics, the whole of the 
vegetable species inhabiting our globe might have assigned to them a climate whose 
temperature would be exactly such as they naturally experience in their respective 
degrees of latitude ; these embracing all that man has yet been able to explore. 
However startling this assumption may appear, it is confirmed by indubitable facts. 
The proofs of its verity are profusely furnished by nature's great Architect, since, 
on the most insignificant hills, many plants that would flourish in the valleys can 
scarcely be preserved ; while, on the summits of the former, other plants are found 
which, still farther north, seek a lower and more retired position. Cases are by no 
means rare, even in Britain, where, in ascending a hilly range, or isolated mountain, 
the limits of distinct groups of native vegetation may be discovered, each possessing 
a hardier character than the one beneath it, till we arrive at the point, beyond 
which, during the severe months, continued snow performs the part of a protector, 
and the plants, consequently, are less hardy. 
Let us, however, as collectors and cultivators of the vegetable productions of 
all countries, carry our researches beyond this comparatively diminutive, ocean- 
encircled spot, and contemplate, for instance, that incomparably vaster range of 
mountains — the enormous Himalayah. Here is a tract, from the study of which 
great practical assistance and instruction may be obtained. Many thousand feet 
above the base of these mountains, the ordinary tropical plants are met with in the 
greatest vigour ; while below their summits trees are found which will thrive, 
without shelter, in the open ground of Britain. The same phenomenon prevails, 
though to a smaller extent, throughout every elevated region in the world. As 
the sea, with reference to the earth's centre, is at all points nearly on the same 
level, it is very properly chosen as a universal standard from which to calculate the 
* Continued from page 159. 
