go BOTANICAL GAZETTE [FEBRUARY 
and errors from changes in external circumstances are not likely 
to obscure the result. 
The following diagrams give some of the results obtained. 
It will be seen that the effect of cutting the leaf stalk is a prac- 
tically instantaneous fall of temperature, corresponding to Me 
preliminary opening of the stomata, followed by a gradual rise 
toward the zero line. The results, in fact, absolutely confirm the » 
observations made with the horn hygroscope. 
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EXPERIMENT 27, fig. g. April 24,1899. CAMPANULA PYRAMIDALIS. 
A. M. 
9:57-10:27 Zero-line drawn, 7. e. nothing on either bulb. Battery turned 
off and an attached leaf placed on the bulb R, a withered 
leaf being placed on the bulb B. 
10:50 Battery turned on; the R-cool fall in the curve indicating the 
difference between the transpiring and withered leaf. 
10:50-12:57 An irregular R-cool fall due to the stomata on the attached leaf 
(R) opening, as indicated by the horn hygroscope. Between 
10:48 and 12:54 the moisture of the air decreased from 70 
per cent. to 61 per cent., so that the whole of fall in the curve 
was not due to the opening of the stomata. 
P. M. 
12:57 Leaf on bulb R severed: a sudden R-cool fall lasting for about 
and is thus rendered distinct, 
