Effect of Plants upon the Air. 191 



EFFECT OF PLANTS UPON THE AIR. 



All nature is in a continual state of decay and renovation. 

 rpjj e perishing remains of animals and plants exhale putrid 

 effluvia* which mix with the atmosphere, and render it impure; 

 the incessant action of respiration through the whole animal 

 world) increases the impurity by abstracting the vital air or 

 oX ygen, and substituting foul air or carbonic acid. This com- 

 bined action has been going on from the beginning of the 

 present order of created things, and yet it does not appear that 

 the air we breathe is less suited to our constitutions now, than 

 itwas in the beginning. This is owing to the agency of plants, 

 which existing wherever man or animals can exist, are perpet- 

 ually at hand to catch up and consume the impure particles of 

 the atmosphere, as fast as they are generated, and by fixing 

 the carbonaceous part in their own systems, and again libera- 

 ting the vital air or oxygen with which the former was in com- 

 bination, they restore to the air all the purity which it had lost. 

 Here, then, you have another of those admirable proofs of 

 wisdom and design that meet the philosophical observer at 

 every step. Plants are Nature's eternal laboratories for the 

 decomposition of what would be injurious to man and other 

 animals ; the means by which the nicest equipoise is main- 

 tained between two most important opposite principles. Hence 

 it is that the most tiny grass, or the most obscure weed, be- 

 comes in the hands of Providence an efficient means of 

 working out the great designs of the creation. 



This is not a phenomenon, liable to derangement or inter- 

 ruption, but ordered with the most admirable precision in every 

 portion of its details. Thus, for example, although it is through 

 the agency of leaves that the salubrious effect upon the air is 

 brought about, yet we are not to suppose that when the leaves 

 have dropped from the trees, and the forest exhibits nothing 

 but bare and naked branches, this agency is diminished. 

 Leaves fall off indeed in winter, but at that time the corruption 

 of the air, by the putrefaction of organized matter, is either 

 arrested or very much diminished, and the green carpet which 



