HABITATIONS OF PLANTS. 
265 
it is by slow removals that they can be made to grow in foreign 
situations. Rice by a slow progress has advanced from Caro- 
lina to Virginia, and it is now cultivated in New Jersey. The 
habifs of Indian corn aided byclimate and culture, have suffered a 
still more remarkable change. After having been several years 
raised in Canada, it arrived to perfection in a few weeks, and 
on that account is employed by us as an early corn. But that 
which has been long cultivated in Virginia, will not ripen in a 
New England summer ; yet, originally, the early corn of Can- 
ada and that of Virginia were the same, both in habit and other 
properties. 
Agents which affect the growth of plants. 
Of the various substances by -which vegetables are nourished, 
water is thought the most important. Some plants grow and 
mature, with their loots immersed in water, without any soil ; 
most of the marine plants are of this description. 
Atmospheric air is necessary to the health and vigor of plants; 
if a plant is placed under a glass into which no air can enter, it 
withers and dies. 
Most plants are found by analysis to contain a certain por- 
tion of salts, such as nitre, and muriate of soda, or common 
salt. It is thought that the root absorbs them from the soil by 
which it is nourished. 
No plants have been made to grow without heat , though some 
require a greater portion of it than others. 
Plants may be made to grow without light , but they will not 
exhibit the verdure, or any of the properties of health. The 
atmosphere, which is contaminated by the respiration of ani- 
mals, is restored to purity by the vegetation of plants ; but se- 
cluded from light, vegetables are no longei capable of convert- 
ing a portion of tl*e fixed air to their use, or of supplying the 
atmosphere with oxygen, on which its importance in supporting 
animal life chiefly depends. By the action of light, the carbon 
of the fixed air is interwoven with the texture of the plants. 
The aromatic plants, the clove, cinnamon, and the Peruvian 
bark, all owe tlieir chief excellencies to the light of the sun. 
HABITATIONS OF PLANT8. 
Plants are not thrown by chance over the surface of the 
globe, but we perceive that the Creator has regulated their dis- 
tribution according to certain fixed principles ; we find not only 
Of rice and Indian com. Agents which affect the growth of plants — 
Water — Atmospheric air — Salts — Heat — Light. Habitations of plants. 
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