1 42 LEAVES. 



very different degrees. This was abundantly proved 

 by the experiments of Bonnet. He placed the leaves 

 of various plants on the surface of water, in order to 

 ascertain the relative absorbing power of different 

 leaves ; and also, of the different surfaces of the same 

 leaf. His experiments, so easily performed, have been 

 repeated by others, and their results are too curious to 

 be unknown. A singular difference has been observed, 

 between the leaves of trees and herbaceous plants, the 

 former absorbing chiefly by their inferior, and the latter 

 by their upper surface. One of the plants which Bon- 

 net employed, was the Purple-leaved Amaranth ; and 

 though it lived not a week, with its inferior surface on 

 the water, it retained its vigour several months, when 

 its position was reversed. On the other hand he placed 

 the upper surface of the Mulberry leaf on the water, 

 and it continued healthy about six days, when it began 

 to droop. He placed by its side another leaf, from the 

 same tree, with its inferior surface on the water, and in 

 that position it remained six months, before it lost its 

 vigour and health. To prove that absorption really 

 converts the vapour of the atmosphere to its own use, 

 we have only to place one of two leaves, which are 

 connected together, in a proper situation to imbibe 

 moisture, and the fluid absorbed, is frequently sufficient 

 to support them both. When speaking of Parasitic 

 plants, I mentioned the Epidendrum or Flower of the 

 Air, which trails over the wall* of the Indian's cottage, 

 and is prized by him for the perfume of its blossoms. 

 Yet this plant is sustained entirely by the moisture 

 which its leaves imbibe from the air of the same room, 

 through which it diffuses its delightful fragrance. 



A knowledge of the exhaling, and absorbing power 

 of leaves, is often of great practical importance. It 



