UPWARD TRANSPORT OF ORGANIC MATTER 



29 



deficiency of osmotically active substances. Chandler 

 (1914) has clearly demonstrated that if tissues having 

 different osmotic concentrations are organically connected, 

 the tissue having the higher concentration will withdraw 

 water from the other when water becomes deficient, causing 

 the latter to wither. 



To test the effects of the treatments upon the osmotic 

 concentrations of the shoots, the freezing-point depressions 

 of the saps of a few shoots were determined. Instead of 

 extracting the sap, the shoots were crushed and the freezing 

 point of the pulpy mass was determined in each case. 

 Fresh weights, dry weights, and sugars soluble in 80 per cent 

 alcohol were also determined. For these determinations 

 all the older leaves were removed and the stems with 

 terminal buds only were tested. 



Table 5. — Effect of Ringing and Removal of Leaves on Growth, 

 Osmotic Concentration and Sugar Content of the Shoot 



These data, summarized in Table 5, show that the 

 osmotic concentration of the ringed defoliated shoots is 

 distinctly less than that of the other shoots. It seems 

 highly probable, therefore, that when wilting took place, 

 it was due, not to a direct effect of the ring on water move- 

 ment through the xylem, but to an effect on solute dis- 

 tribution, and this in turn on the ability of the tissue to 



