USES OF LEAVES. 14i> 



ing cause — while it assured him and us, that every part 

 of the creation is controlled by the Wisdom of an Infi- 

 nite Mind. By a series of experiments conducted with 

 his accustomed ingenuity, he ascertained that growing 

 plants imbibe carbonic acid and expire oxygen gas. The 

 leaf of a Vine was introduced into a phial of the former, 

 and in less than two hours the fixed air disappeared, and 

 oxygen gas was found in its place. If leaves be intro- 

 duced into an inverted tumbler of water, and exposed 

 to the influence of the sun's rays, bubbles of air will 

 appear on their surface. They consist of nearly pure 

 oxygen gas, but if the same experiment is performed in 

 the dark, the air evolved does not possess the same 

 degree of purity. Thus we learn the mutual depend- 

 ence of the two living kingdoms of nature upon each 

 other, the beauty and harmony of creation : Man ex- 

 pires the food of plants — plants exhale what has been 

 emphatically denominated the breath of life. 



After the experiments of Priestly, it was supposed 

 that respiration deprived the air of that oxygen, which 

 is restored by the vegetation of plants. This theory, 

 so satisfactory, and apparently so well established, has 

 been received till lately without a doubt. Within a few 

 years, however, Mr. Ellis has performed some experi- 

 ments, which lead him to reject the opinions of Priest- 

 ly, and to insist on the one effect of organized living ex- 

 istence ; and he maintains that the germinating seed, the 

 vegetating plant, and the respiring animal, all produce 

 the same changes, all increase the carbonic acid and di- 

 minish the oxygen of the atmosphere. Whatever credit 

 is due to this gentleman for the ingenuity of his expert 

 ments, they do not appear to justify his conclusions, and 

 his opinions are yet to be established by additional 

 proof, or else entirely rejected ; for they are not con- 



14 



