264 BOTANICAL GAZETTE [ocTOBER 
from all injury. The final measurements show that the plants 
grew well. The experimental plants increased 152 per cent in 
height, 131 per cent in the diameter of the weighted portion, and 
122.5 per cent in the diameter a short distance above the weighted 
part; the control plants, in the same positions and dimensions, 
142 per cent, 135 per cent, and 133.7 per cent respectively. The 
relative amounts of xylem for the experimental and the control 
plants were 95.17 and 100 respectively. Careful measurements of 
cell walls showed no difference between the experimental and the 
control plants. 
SUMACH (ONE-YEAR-OLD PLANTS) 
From a very large number of thrifty sumach sprouts 24 one 
year-old plants were selected for experimentation. In April these 
plants were tied to stakes, and weights were placed upon the experl- 
mental plants in the usual manner. Conditions were fairly good 
during the growing season. The plants were kept under experl- 
mental conditions until October, although nearly all of the growth 
in size and thickness of stem took place in the spring and early 
summer. The final measurements and tests showed that the 
experimental and the control plants were practically equal in size 
and strength at the end of the season. A comparison of the actual 
increase in xylem, as determined from the annual rings, showed 
about 18 per cent less for the experimental than for the control 
plants. Careful examinations and measurements showed no differ- 
ence in the size of cells or in the thickness of cell walls. 
SUMACH (YOUNG PLANTS) 
Sixteen young plants were placed under experimental conditions 
_as soon as they had attained a height of about 35 cm. ‘These plants 
did not increase greatly in size and thickness of stem. The tests 
and measurements showed that the strength and amount of xylem 
were very nearly equal for the experimental and the control plants. 
The percentage increase was somewhat greater for the experimental 
plants than for the controls. This difference, however, loses 18 
significance when we observe that the actual increase in height wa 
only 6.93 cm. for the experimental and 5.11 cm. for the control 
plants, and the increase in diameter only 2.07 mm. and 1.75 mm. 
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