THE LEA VES. I4I 



of water to this crevice, and its freezing, serve to rujiture the 

 remaining tissues, and thus allow the leaf to fall by its own 

 weight, or to be torn off by the wind. 



The scar left by the fall of the leaf is protected either by 

 the cork already produced, or by mere dr\ing of the exposed 

 tissues. The leaflets of compound leaves fall in like manner. 

 Sometimes [jrovision for the leaf fall is begun as early as June, 

 as_in the Kentucky coffee-tree. In other plants provision 

 lor leaf-fall is begun late in the season, and in some, such as 

 the oaks, it is \'ery imperfect, so that the leaves are finally 

 wrenched off by winter storms, or pushed off in the spring by 

 the developing buds beneath them. 



