478 BOTANICAL GAZETTE [JUNE 
the winter of 1911-1912 (GATES 19). The bushes of Chamaedaphne 
were uniformly killed down to the snow level. This might have 
been due to the cold itself, but more likely was the result of exces- 
sive drying beyond the limits of the plants to recuperate. The 
difference in temperature at the snow level and 3 cm. below it was 
scarcely noticeable, upon the occasions when it was determined, 
during the moderately cold weather (—15 to 20°), yet above the 
snow line the plants died. At low temperatures the absolute 
amount of water vapor that can be in the air is very low, but below 
the line of snow the airis saturated. This argues for death by dry- 
ing rather than by freezing, for the leaves below the snow line have 
more chance to keep within the drying limits of their protoplasm. 
EXPERIMENTATION UPON THE CONDITION OF THE STOMATES 
As has already been outlined, the data obtained upon this 
question are based upon the time it took a penetrating liquid (xylol) 
to render the leaf translucent. Different species varied in the 
readiness with which they became translucent, but a little experi- 
mentation soon sufficed to disclose a ‘‘normal’’ rate upon which 
to base deductions. 
During the entire course of the experiments upon the several 
species of bog plants, the relative time of penetration indicated 
that the stomates were always open during the time that the full 
sun shone upon them. For many plants the diffuse light of early 
morning was sufficient to open the stomates partially, but it did not 
always appear that they were wide open until the full sun shone 
upon them. In other species, as Nymphaea advena, the stomates 
did not open until the direct sun reached the leaves. So far as 
was observed, clouds did not cause the closing of the stomates on 
hot, dry days, but on cloudy days the stomates closed earlier in the 
afternoon than on sunny days. 
Just after the time of maximum transpiration and maximum 
evaporating power of the air, the stomates begin to close. The 
rate of transpiration drops very quickly, but stomates close slowly, 
and in most of the species are not completely closed until after 
dark. Ina few species, as Salix pedicellaris, there was no evidence 
that the stomates ever closed 
