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complete dryness of the soil would not 

 then injure them. If this were so, when 

 trees were cut down at Midsummer, till 

 the fall of the leaf, the heads would remain 

 alive, and the roots would immediately die. 

 The reverse of this is the case ; the roots 

 remain alive, and shoot out without any 

 assistance from the atmosphere, and the 

 heads immediately die. 



It is certain that great chemical changes 

 or elaboration of the sap must take place 

 in the root or stem before it reaches the 

 leaf ; since sap of very different qualities 

 is drawn from the stems of different trees. 

 Witness the sugar from the maple and 

 birch, the resin from the fir, &c., &c., 

 which are found in the heart wood. Also 

 the alteration of the heart wood in den- 

 sity, and the change of alburnum into 

 heart wood, argue elaboration in the stem 

 and deposit from the upward sap. This 

 opinion also seems to be supported by 

 the fact, that when a peach is grafted 



