14 
IOWA ACADEMY OF SCIENCE 
The psychrometric and barometric readings showed little variation in 
air pressure, and humidity. The leaves were cut off even with the cork 
at the end of each experiment and weighed. 
The results show (1) That in every cas^ of plants exposed to the 
strongest current, a checking of transpiration occurred. (2) That the 
plants at the two middle stations showed greatest loss of water, while 
"from the plant in quiet air, less was given off. 
Even when the strongest current caused complete wilting (as it did 
in several plants, i. e., geranium, box elder, etc., before Clivea was hit 
upon) the loss of water was little, or none. 
The stomata of the Clivea have not been examined under the con- 
ditions of the experiment, but the geranium used at first showed the 
guard cells greatly disturbed, but not consistently so, on one leaf some 
being closed, some open and some in intermediate stages. 
As an example of the results obtained — one table shows as a total 
of observations taken every two hours during one day: 
Station 1. .5 gr. wt. of leaf 19.6, 
Station II. .7 gr. wt. of leaf 16.6, 
Station III. .11 gr. wt. of leaf 14.2, 
Station IV. (Quiet.) .55 gr. wt. of leaf 13.3. 
Another series — reading taken at intervals of II /2 hours during a day 
and a half (night reading being eliminated on account of a fall of 
temperature which could not be recorded.) 
Station I. 1.2 gr. wt. of leaf 19 gr. 
Station II. 2.3 gr. leaf wt. 14.5, 
Station III. (Quiet). .4 gr. leaf wt. 10.4. 
The results of the experiments thus far carried out indicate that 
air-currents of greater velocity check, while gentler currents stimulate 
transpiration. 
A number of interesting incidental observations were made. For 
example, one which showed a structural difference developed by dif- 
ference in environment as regards light and air. 
In one end of the plant house the geraniums brought in from the 
grounds last fall were cut back and set out crowded very closely. The 
leaves they bear now were developed under the plant house conditions. 
Two leaves from each of six plants were examined, one from the top, 
exposed freely to light and air, the other from underneath, shut away 
from air-currents and with reduced light. In every case the exposed 
leaf was found to have fewer and much larger guard cells with much 
wider stomata. (Lloyd’s method of fixing stomata being used in all 
the observations on stomata.) 
