63 



the root is consequently in a state to 

 supply the great upward demand next 

 spring. 



We may convince ourselves by experi- 

 ment, that the downward is after the 

 upward growth of trees. If notches are 

 cut on the stem of a tree from the root 

 to the setting on of the first branches, 

 the new growth over the scars will be 

 when the tree is ceasing to shoot. The 

 upper notches will heal first, in the form 

 of a horseshoe, with the heels down- 

 wards, that is, the growth will be on the 

 upper part and the sides of the notches, 

 without any growth from the lower 

 parts of the notches. This fact also 

 strongly corroborates the opinion that 

 the new growth in diameter is from the 

 downward sap ; for if it were a side 

 deposit from the upward sap the lowest 

 notches should heal first. I have found 

 that if stems thus notched are inverted, 

 the new growth comes only from the sides 



