THE PLANT 



43 



through the young wood to the leaves, and one, a down- 

 ward current, passes through the bark, carrying needed food 

 to the roots (see Fig. 28). 



If you should injure the roots, the 

 water supply to the leaves would be 

 cut off and the leaves immediately 

 wither. On the other hand, if you 

 remove the bark, that is, girdle the 

 tree, you in no way interfere with 

 the water supply and the leaves do 

 not wither. Girdling does, however, 

 interfere with the downward food 

 current through the bark. 



If the tree be girdled, the roots 

 sooner or later suffer from lack of 

 food supply from 

 the leaves. 

 Owing to this 

 food stoppage, 

 the roots will 

 cease to grow, 

 and will soon be 

 unable to take in 



sufficient water, and then the leaves will 

 begin to droop. This, however, may not 

 happen until several months after the FlG 29 A THICKEN- 

 girdling. Sometimes a partly girdled ING ABOVE THE WIRE 

 branch grows much in thickness just 

 above the girdle, as in Fig. 29. This 

 extra growth seems to be due to a stoppage of the rich 

 supply of food which was on its way to the roots through 



FIG. 28. MOVEMENT OF 

 THE SAP CURRENT 



THAT CAUSED THE 

 GIRDLING 



