160 EXPERIMENT STATION. [Jan. 



as the sbodl will uutgruw it in from three to five years, and does 

 not seem to suffer any serious ill effects from the trouble. 



(5) It is caused by a sudden disruption of the metabolic 

 processes of the tree, all leaf activity being suspended ; and there 

 being no normal relationship between root metabolism and leaf 

 metabolism, the new shoot is unable to properly bring into avail- 

 able form the food supplied for the nourishment of the tree. In 

 other words, there is an attempt on the part of the leaves to cor- 

 relate their functions with a root area many times larger, and 

 consequently a pathological condition is set up within the tissue, 

 due, as has before been said, to imperfect metabolism. 



