366 
AMERICAN JOURNAL OF BOTANY 
[Vol. io, 
It is evident from the data on the nitrogen content that ringing has 
resulted in a lessened amount of nitrogen in the leaves whether expressed 
as milligrams of nitrogen per leaf, per gram of dry matter, or per unit of 
leaf area. The small amount of nitrogen per leaf and per unit of weight 
might be expected, because the leaves are smaller and the dry weights are 
relatively high because removal of the carbohydrate has been retarded by 
the ring. The small amount of nitrogen per unit of leaf area, however, 
is a good indication that relatively less had been carried up the ringed 
stem, for otherwise one would expect more nitrogen as the leaves are thicker 
and heavier per unit of area. Furthermore, there was nothing to prevent 
the removal of proteins or other forms of nitrogen from the check leaves 
back to the trunk or roots, while such removal from the other leaves would 
have been retarded by the ring. The total amount of nitrogen moving 
up the unringed stem was certainly much greater than that moving up 
the ringed stem, for there were from ten to twenty times as many leaves 
on the check stem, and these leaves were also larger, usually from 30 to 
70 percent, than those of the ringed stem. 
Though nitrates have been found in abundance in stems (Berthelot and 
Andre, 1886), and organic nitrogen compounds have been found in solu¬ 
tions bleeding from cut stems (Schroeder, 1871), it is conceivable that 
much of the nitrogen might be transformed into protein which probably 
would be more readily carried in the phloem. In order, therefore, to de¬ 
termine if the rings had also retarded the upward movement of those 
nutrients which might be less likely to combine with organic matter and 
which have been found in abundance in the solutions bleeding from cut 
stems (Schroeder, 1871, and others), and which, therefore, are commonly 
considered to be carried in the “transpiration stream,” the ash contents 
of a number of samples were determined. These data are also presented 
in table 1 for comparison with the nitrogen analyses. 
In the most complete and dependable set of analyses, those for tree 
number 1, the leaves from the ringed stem have only 76 percent as much 
ash per unit of area as the checks, while per unit of dry weight they have 
only about 67 percent as much. The few analyses of samples from the 
other trees indicate similar differences. 
Another experiment in some respects comparable with this one with 
peach trees was tried with a lilac bush. A stem three centimeters in diame¬ 
ter was ringed August 6, 1920. No leaf samples were taken at this time, 
however, and no nitrate was added to the soil. On July 30 of the follow¬ 
ing year (1921) other stems of this same bush were ringed and sodium 
nitrate was added to the soil. Leaf samples from the branch ringed the 
previous year, as well as from the newly ringed and check branches were 
taken at this time and again on August 22 and September 9. The shoot 
growth on the ringed stem was distinctly less than that on the check stem, 
the leaves were smaller, thicker, less pliable, and were distinctly yellowish 
