CARBON DRAWN FROM THE AIR. 81 



the soil with decomposing matter and prepare it for a bet- 

 ter product; and plants procuring a portion of their carbon 

 from the air and gradually finding an increased supply in the 

 soil from the decomposed organic matter, there would, in 

 time, be a surplus, and this surplus would constantly in- 

 crease, and gradually accumulate and fill the soil. In the 

 other case the vegetation would be developed on an enor- 

 mous scale, just as we have reason to suppose it was at the 

 period when the carbonaceous matter which supplied the 

 materials for the vast coal beds was deposited. Climate 

 necessarily would have much to do with this, as it has now; 

 for in tropical regions the vegetation is exceedingly luxu- 

 riant, forming dense jungles through which it is impossible 

 to pass without laboriously cutting a way with axes, over an 

 enormous deposit under foot of the tangled and decompos- 

 ing remains of previous luxuriant growth. 



We are forced to believe from the evidence that plants 

 may derive a large portion of their carbon from atmospheric 

 sources, and that they derive a considerable portion of it 

 from the soil. That they are fitted by nature to draw sus- 

 tenance from either source or from both; and that the pro- 

 portion of their food which is derived from either source 

 depends upon a variety of circumstances ; such as the nature 

 of the plant; the period of its growth; on the soil; on the 

 abundance of provision furnished by the soil; upon cli- 

 mate; season; and other circumstances; so that the most 

 reasonable conclusion would be, that plants, like animals, 

 have a power of adapting themselves, to a certain extent, 

 to the conditions in which they are placed, and of finding 

 aliment, and supporting life, and of making growth, by the 

 help of such nutriment as they may most easily reach. 

 Just as sheep, which are herbivorous animals, under cer- 

 tain conditions are known to live upon fish, and to thrive 

 as well to all appearances upon this unusual diet, as upon 

 the pastures. 



But supposing that plants derive the whole of their car- 

 bon from the air, or are able to do so; then knowing that no 

 other compound of this element is found in the atmosphere 



