TREE PRODUCTS 129 



facture is clearly enough understood. All other 

 deciduous trees must supply nutriment in similar 

 way to their growing buds. 



But in the case of other trees, either the sap 

 will not flow in abundance or it is of such 

 quality as to have no value. 



The manner of production of the sap may be 

 more or less accurately inferred from what we 

 have already learned of plant physiology. We 

 know that the leaves of the tree metamorphose 

 water and carbon into sugary substances which 

 in turn are transferred to various parts of the 

 plant to be stored, usually in the form of starch. 

 In the case of the maple, we may assume that the 

 carbohydrates, as they are manufactured in the 

 leaf laboratories, are transferred in the current 

 of sap that flows downward from the leaves 

 through branches and trunk as a countercurrent 

 in the cambium until it finally finds its way to the 

 roots of the tree and is there stored for the 

 winter. 



When spring comes and it is time for the new 

 leaf buds to put forth, the supplies of nourish- 

 ment are retransformed into soluble sugars, dis- 

 solved in the water that is taken in by the root- 

 lets, and transferred from cell to cell and along 

 the little canals in the wood under the cambium 

 layer of the bark, until they reach the twigs 



E Bur. Vol. 8 



