ER Ns tee eer a a ee 
— B.warnM. 
1904 | DARWIN: MOVEMENTS OF STOMATA Tol 
11:55 Vise unscrewed. 
The final result is B-cool, 2. ¢., opening of the stomata; the prelimi- 
nary increased closure, lasting about five minutes, I have not 
observed elsewhere, and is no doubt the expression of the fact 
P.M, that release from compression does not at once take effect. 
1:22 Vise again applied. 
Preliminary opening followed by closure. 
2:19 Vise removed. No effect. This no doubt is due to the vessels being 
so much crushed that their lumens remain closed even when relieved 
from compression. In a second experiment on Aug. 24, 1900 with 
another branch of Clematis montana the preliminary opening, 12 
minutes, and closure, 24 minutes, were clear, but the effect of remov- 
ing the vise was very slight. When, however, the branch was cut 
under water between the vise and the leaf, an immediate cool-move 
occurred. 
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Fic. 13.—See Experiment 97, p- 100. 
I have discussed (loc. cit., p. 556) the question whether the 
increased transpiration which generally follows the relief from 
compression is really due to the opening of the stomata, or 
whether the sudden rush of water into the leaf could produce 
the effect, even though the stomata remained half closed. I see 
no way of deciding the question. 
