42 



water to the leaf. Frost alone, as previously remarked, 

 may not be competent in all cases to effect this change, as 

 in the semi-evergreens, Lonicera Halleana, etc., the reason 

 being probably that when frozen roots, stems and leaves are 

 in the shade and the atmosphere be not too dry, there would 

 be little or no transpiration, and with return of milder 

 weather the leaves might wholly regain their lost functions 

 without any change of color or serious damage to their 

 tissues. 



It is undoubtedly the frosty nights followed by warm suns 

 that changes the foliage of the oaks and all other remaining 

 foliage capable of change, represented by a large number of 

 different species. Before the frosts arrive, individual oaks 

 may change from drought the same as other trees, but whole 

 forests do not often so suffer, and yet they regularlj^ change 

 color rapidly and within a few days after the severe and 

 late frosts of October. About November 5 they are iii their 

 brightest and best tints of reddish brown, yellowish brown, 

 purplish tan, dull purple gray, and similar tones. 



December 1, 1900. 



