THE DIFFUSION OF VEGETATION. 15 
nitely, but no one of the fragments, alone, will still be a complete 
plant. 
11. Animals, like plants, are organized bodies, endowed with 
vitality, and composed of distinct parts, no one of which is com- 
plete in itself; but they are raised above either plants or min- 
erals, by the power of perception. 
a. These distinctions, long since suggested by the immortal Linnzus, are per- 
fectly obvious and definite, in the higher grades of the animal and vegetable 
kingdoms; but, in descending the scale, we recognize a gradual and constant 
approach, in both, to inorganic matter, and consequently to each other; so that, 
in the lowest forms of life, all traces of organization disappear, and the three great 
kingdoms of nature, like three converging radii, meet, and blend in a common 
centre. 
/12. Vegetation, in some of its forms, appears to be coezten: 
sive with the surface of the earth. It springs up, not only from 
the sunny soil, moistened with rain and dew, but even from the 
naked rock, amidst the arid sands of the desert, in thermal and 
sulphurous springs, in arctic and alpine snows, and from the beds 
of seas and oceans. 
a. Among the multitude of natural causes which affect the growth of vegeta- 
tion, the action of the sun, through the light and heat which it imparts, is the most 
efficient. This is most powerful at the equator, and gradually diminishes in in- 
tensity, as we proceed from thence towards either pole. Vegetation, therefore, 
arrives at its highest degree of luxuriance at the equator, and within the tropics. 
In the temperate zones it is less remarkable for the beauty and variety of its 
flowers, and the deliciousness of its fruits, than in the torrid; yet it is believed to 
be no less adapted to promote the arts of civilized life, and the well-being of man 
in general. In still higher latitudes, plants become few, and of stinted growth, 
until finally, within the arctic circles, they apparently, but not absolutely, cease 
to vegetate. 
.~b. Since climate is affected by elevation above the level of the sea, in the same 
manner as by increase of latitude, we find a similar diminution of vegetable 
activity, in ascending high mountains. Thus, the peak of Teneriffe, situated on 
a fertile island, within the tropics, is clothed, at different elevations, with plants 
peculiar to every latitude, in succession, from the torrid to the frigid zones, 
while the summit, being always covered with snow, is as barren as the region of 
the poles. So also the White Mountains, in New Hampshire, exhibit upon their 
‘summits a vegetation similar to that of Labrador, or even Greenland. 
c. One of the first requisites for the growth of plants, is a soil, from which, by 
means of roots, they may derive their proper nutriment and support. But numer- 
ous species of lichens and mosses find their most congenial habitations upon the 
bare rock. The coral island no sooner arises to the surface, than it arrests the 
Q* 
