LEAVES OF TREES 



217 



forms the rough coat, in which most trees are 

 clothed, and a new inner bark is formed." 



Now as to the Leaves^ their use to the 

 plant that bears them is not so evident ; but 

 it is now generally understood, that the air 

 has upon them a chemical effect, needful to the 

 life of the whole ; for if all the leaves be picked 

 off, the plant languishes, or dies. Their uses 

 for man are too numerous to be named at pre- 

 sent. The leaves of most trees, having lasted 

 during the warm and genial season, die and 

 drop off ; not merely by their own weight, but 

 by the action of the plant itself." 



But in hot countries," observed Mr. Long- 

 hurst, this is not the case. The trees there 

 do as evergreens with us ; they lose their old 

 leaves, only as new ones come ; so there is 

 no ' general fall of the leaf,' as in the colder 

 climates." 



