374 
AMERICAN JOURNAL OF BOTANY 
[Vol. io, 
analyzed separately at the close of the experiment. Forty-two stems were 
selected for the experiment. These were chosen in pairs as they grew 
on the bushes of a hedge, and one of each pair was ringed while the other 
was left as a check. Sodium nitrate together with smaller amounts of 
calcium chloride, sodium chloride, and calcium carbonate were added to 
the soil around the hedge. The application was not very uniform because 
the bushes were growing close together and the bunches of sod beneath 
the bushes made uniform application difficult. This probably accounts 
very largely for the difference between the series taken October 3 and that 
taken October 4, since the two series were from different parts of the hedge. 
The data are presented in table 5. 
From these data it is evident that there was a distinctly smaller increase 
of nitrogen in the leaves of the ringed stems whether this is considered as 
an increase in absolute quantity of nitrogen, or in the amount per unit of 
leaf surface. The amount of nitrogen per unit of dry weight shows, in 
every case, a loss in the leaves of the ringed stems. This was due very 
largely, of course, to the marked increase in dry weight of those leaves. 
The data for the stems show that there is a greater amount of nitrogen 
per gram of twig in the checks than in the ringed stems. This is true in 
both the basal and the upper parts of the stem. The smaller amounts in 
the ringed stems are not merely apparent and due to the greater dry weights 
of the ringed stems which resulted from an accumulation of food, for, in 
each of the nineteen pairs of twigs analyzed in the three series, the check 
stem had not only a greater amount of nitrogen per unit of weight, but 
it had, with but two exceptions, a greater absolute amount of nitrogen 
than had the corresponding ringed stem. In one of these cases the basal 
part of the check stem had an unusually low amount of nitrogen, so low 
that it was evidently due to an error in analysis, and in the other case the 
ringed stem was not well matched with the check, but was distinctly larger, 
which fact would easily account for the greater total nitrogen. 
In the series harvested Nov. 19, the wood and bark of the twigs were 
analyzed separately. The results of these determinations are given in 
table 6. The data for the leaves and for the entire twigs are included in 
table 5. 
It is evident from table 6 that the ringing has resulted in a distinct 
increase in the weight of the bark, especially in the twenty centimeters 
immediately above the ring. This effect on the bark is even more clearly 
indicated by the increase in the ratio bark: wood, both in the basal and 
in the upper parts of the stem. The ratio between the amount of nitrogen 
in the bark and that in the wood is also increased by ringing. 
The ash contents of the stems were not determined because of the 
small amount of material and the difficulty of dividing the samples, but 
those of the leaves were obtained and are presented in table 5 for compari¬ 
son with the nitrogen. The results of the ash determinations correspond 
