1914] GATES—X EROPHILY 465 
spiration, a number of experiments were made in the laboratory, 
the results of which are summarized in table I. 
TABLE I 
SUMMARIZING THE EFFECT OF LOWERING THE TEMPERATURE OF THE SOLUTION UNDER 
THE SAME EVAPORATING POWER OF gion cae THE TRANSPIRATION IS EXPRESSED 
IN GRAMS PER HOUR PER I00 SQ. THE NUMBER OF MEASUREMENTS 
UPON WHICH THE AVERAGE IS pay Is pecan IN PARENTHESES 
Under room conditions (temp. 18-25° C.; rel. hum. 30-40 per cent) 
Solution at room | Solution at freezing 
temperature temperature 
Chamaedaphne  oemnengrent association).. 0.062 (13) O. ie (13) 
Chamaedaphne (Carex association)............. 0.080 ( 2) 0.068 ( 4 
Chamaedaphne (Larix sence Ae pete aie ae 0.042 ( 2) 0.042 ( 3) 
Larix laricina (Larix association)............... 0.022 ( 4) 0.028 ( 4) 
Under radiator conditions (temp. a C.; rel. hum. 4-20 per cent) 
Solution at radiator | Solution at freezing 
temperature temperature 
Chamaedaphne (Chamaedaphne association)... .. | SSO pIAT ATS) | 0.067 (11) 
In the course of these experiments cuttings were made during 
the cold snowy weather of February and March 1912, and subjected 
to different conditions in the laboratory. The laboratory condi- 
tions of temperature and relative humidity are more extreme than 
these plants are ever naturally subjected to in winter. 
To determine the influence of a cold source of water supply, 
twigs were set up in water in bottles, set in a snow mixture, which 
kept the temperature of the solution at or near freezing. Other 
twigs set up in the room gave data for comparison. The general 
results show a lower rate of transpiration from the colder solution. 
The effect, however, is not so pronounced as might be expected. 
The control was much less perfect in leafless twigs than in leafy 
ones. Leafless twigs have occasionally shown a higher rate of 
transpiration from the colder solution. This is probably due to 
the stimulation which is the first effect of application of cold (BosE 
2). Such a higher rate, however, is only temporary, although it 
has continued for 10 hours in some of the leafless twigs experi- 
mented upon. Warming the solution was uniformly accompanied 
by a rise in the rate of transpiration. A lowering of the rate of 
