Lioyp: LEAF WATER IN GOSSYPIUM 11 
to its roots could be determined by following the changes in leaf 
water from day to day, and so anticipate a condition of necessity 
which might curtail growth for a period. Obviously such a pro- 
cedure would be of practical use only where water is under control. 
We now turn to consider the tables which present data relative 
to a constant leaf area, namely 100 square centimeters. 
For the purpose of comparison in what follows, the data em- 
bodied in TABLES v—vitI inclusive have been segregated in two 
sets of graphs, those (in F1G. 2) for young or full-grown but not old 
and indurated leaves, and those (FIG. 3) for old leaves, rather the 
worse for wear. They were indurated, torn and more or less 
discolored, but a consistent effort was made to collect the material 
from leaves with a healthy appearance. The three series (1 to 3 
incl.) for Tucson, Arizona, are included if FIG. 2, since the leaves, 
while mature, were not at all indurated and, indeed, had perhaps 
not arrived at full growth, though they were well developed. 
Of the seven series of samples from young leaves one only, 
viz. no. 4, appears to indicate an aberrant behavior, especially as 
to increase in dry weight, but evidently so as to the loss of water 
also. If we disregard this case, for which no explanation is offered, 
the remainder show a general accord. Of the six remaining cases, 
two (2 and 3), those for Arizona, show an increase considerably in 
excess of those for Alabama. The ratio of increase for Arizona is 
100 to 120 for the first four hours and 100 to 136 for the whole 
period of eight hours, beginning at 6.20 for the first series; the 
ratios for the second series are 100 to I12 and 100 to 124. In 
Alabama the greatest gain for a like period was in the ratio of 
100 to 121, while the lowest was from 100 to 109. 
Stated in terms of increase of photosynthates, we have for 
the Arizona plants an accumulation at the rate of 2.25 grams 
per hour per square meter for the first four hours, and 2.00 grams 
for the second four hours, for no. 2, TABLE V; the corresponding 
figures for no. 3 are 1.50 and 1.50. For the young leaves of Ala- 
bama plants, excluding series 7, TABLE VI, the range of increase 
(when there was any increase at all) is from 0.5 to 1.6 grams. 
Sachs’ determinations for the sunflower were 1.88 and 1.7, and 
for the cucumber 1.5 gr. Brown and Escombe’s datum for the 
sunflower is, however, 0.714 gr. Although my own data were 
