118 On the Influence of Climate on Plants and Animals. 



tend at the same time to ameliorate the great heats of those 

 regions, and to prevent the polar regions from becoming 

 blocked up with accumulating mountains of ice which, but 

 for this provision, would soon be pushed down as extensive 

 glaciers, rendering whole tracts of our temperate zones unin- 

 habitable wilds. Dr Scoresby concluded by pointing out se- 

 veral meteorological influences of these currents, by causing 

 extensive fogs, and winds more or less violent. 



On the influence of Climate on Plants and Animals. By 

 Dr Emmons of New York. 



It is difficult to determine the influence of climate on or- 

 ganized beings. The influence of climate seems, however, 

 to modify what exists ; it spends itself on those bounds, it 

 does not form, but modifies varieties. Light, no doubt, should 

 be regarded as an element of climate ; its duration and in- 

 tensity are indications of its force, and measures its activity. 

 We see the foliage of a forest becoming more deeply green 

 as we go towards a tropical region ; the herbage of a species 

 of forest tree becomes stiffer, rigid, and less leafy, as we go 

 north, or ascend the mountains; and we may trace the changes 

 in our ascent, until we find it a dwarf, a diminutive tree, a 

 mere shrub, upon the heights of .a mountain, while in the plain 

 at its base it is a lordly tree. Those changes are unques- 

 tionably due to climate ; they are not those which charac- 

 terize varieties, much less species : indeed it is important 

 that we do not assign too much to climate. Some naturalists 

 have supposed that climate produces varieties ; it seems, 

 however, more consonant to facts to infer that varieties are 

 independent of climate ; that the causes which have been 

 operating in the production of varieties have belonged to in- 

 dividuals. These forces or influences are begotten in a civil- 

 ized state, or where many individuals are congregated. 



It is not agreeable to the principles of natural history to 

 maintain that the peculiar vegetation under a tropical sun 

 is due to climate, or that it is an effect of climate. The 

 species of plants belonging to the tropics differ entirely from 



