74 PBANTOM FLOWERS. 



leaf loses its hold oji the parent spray, and finally 

 falls to the ground. 



Chemistry has proved that at this period it contains 

 a large amount of mineral matter. The autumnal 

 leaf contains a much larger proportion than when it 

 was young and succulent ; hence the facility of macer- 

 ation in summer, and the impossibility of doing so in 

 autumn. It is a remarkable fact that the leaf con- 

 tains a larger proportion of mineral matter than the 

 body of the tree. Thus, the dried leaves of the Elm 

 contain more than eleven per cent, of earthy matter, 

 while the wood contains less than two per cent. The 

 Beech, the "Willow, the Pitch Pine, and other trees, 

 present difierences almost as great. 



One of the most remarkable properties of the leaves 

 is their power of decomposing carbonic acid, thus 

 enabling them to contribute, in common with the roots, 

 to the growth of the plant. The largest part of all 

 plants consists of carbon and the elements of water. 

 The woody fibre is formed of carbon, hence the growth 

 and increase of aU trees and plants are dependent on 

 their capacity for taking up and digesting this sub- 

 stance. But they neither find it nor take it up in a 

 free or simple state, but in the form of carbonic acid, 

 that is, carbon combined with oxygen. This carbonic 



