THE FUNCTIONS OF THE WOOD 



191 



TABLE XLIX. 

 SAP OF Populus alba, Au GUST 28, 1913. 



In this case the sap centrifuged from the tracheae of the 

 stem and the root gave no direct reaction with Fehling's 

 solution. Evidently neither glucose nor maltose was 

 present. On inversion, however, a noticeable reduction 

 took place, indicating the presence of sucrose to the 

 amount of about 0*5 per cent, and 1 per cent, respectively 

 in the stem and root. 



The sap from the cells of the bark of stem and root, and 

 from the leaves examined at the same time, showed, as 

 appears above, much higher concentrations. 



It was then determined to investigate the concentration 

 and constituents of the wood sap at different seasons of 

 the year, and to see if variations of any considerable mag- 

 nitude occurred in it. With this end in view, pieces were 

 cut from the branches, at the same level on each occasion, 

 and roots of the following trees, and examined cyroscopic- 

 ally, electrically, and chemically: Acer pseudoplatanus , 



