98 BOTANICAL GAZETTE [FEBRUARY 
EXPERIMENT 17 B, fig. 70. February 23, 1899. NICOTIANA AFFINIS, 
A.M. 
11:3-11:42 Zero line (nothing on either bulb). T. at 11:8 19°, Psy. 74% 
Er: 42 -Attached leaf on bulb R, withered on B. 
P. M, ‘ 
i Plant placed in dry greenhouse. T.27°, Psy. 41% Rapid 
R-cool move owing to the physical effect of the dryness of 
the air. 
1:34-4:54 Gradual R-warm move, indicating gradual closure of stomata. 
The occurrence of closure was confirmed by horn hygro- 
scope readings. 
4:49 2.246", Psy. 37%. 
EXPERIMENT 16, fige 11. February 24, 1899. EEUPATORIUM WEINMAN- 
NIANUM. 
No zero line drawn, but the beginning of the curve is roughly zero. 
#1349 Attached leaf on bulb R ; withered leaf on bulb B. T. at 11:35 20.6" 
. sy. 71%. 
12:40 Moved plant to dry greenhouse. T. 30.8°, Psy. 40%. A rapid R-cool 
move, owing to physical effect of the dry air. 
1:2 A rapid R-warm move, indicating partial closure of the stomata. 
2:52 T. 33°, Psy. 42% A young leaf on the plant showed signs of being 
withered, but the experimental leaf not visibly flagging ; neverthe- 
less it must have been suffering from want of water, as it showed 
no sign of opening its stomata on being placed in damp air. 
Here follow two experiments on the different behavior of dry 
air on plants well and badly supplied with water in the soil. 
EXPERIMENT 87, fig. 72. July 25, 7900. TROPAEOLUM MAJUS. 
Two pots of Tropaeolum, viz., R and B: of these, plant R had been kept 
well watered; B had been kept without water, but was not so dry as to pro- 
duce closure of the stomata, 
A.M. 
9:39 An attached leaf of plant R placed on bulb R. An attached leaf of 
lant B placed on bulb B, 
10:28 The horizontal line ending here shows that the well-watered leaf R 
was considerably the cooler. The leaves were now removed from 
the recorder, and plant B placed in damp air under a bell-jar. 
11:18 Plant B removed from damp air, and again placed on bulb B; leaf B, 
badly watered, is now cooler than it was ; this can only be due to 
the stomata being more open; the difference cannot be due to the 
physical effect of the bell-jar, where, owing to the check to trans- 
piration, it would have been warmer than leaf R, still exposed to 
the air of the greenhouse. T, 23-28°, Psy. 67-s8¢. 
