382 
AMERICAN JOURNAL OF BOTANY 
[Vol. io, 
the influence of altered transpiration or of change in carbohydrate content. 
In this experiment, evidence was obtained indicating that the low nitrogen 
content above a ring is not due to a lessened transpiration or to a changed 
carbohydrate content. 
The data cannot be considered as conclusively proving that nitrogen 
or other nutrients move upward primarily through the phloem and not 
through the xylem, for the treatments may have altered the xylem tissues. 
Aside from such a contingency, however, these data from ringing experi¬ 
ments offer strong evidence indicating that nutrients are carried chiefly 
in the phloem. 
Laboratory of Plant Physiology, 
Cornell University 
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