480 BOTANICAL GAZETTE [JUNE 
daphne calyculata, Aronia melanocarpa, Potentilla palustris, Acer 
rubrum, and Cicuta maculata were kept.in the laboratory window 
submerged in water for a couple of days. Xylol determinations 
disclosed the fact that the stomates were open both day and night. 
Only in Chamaedaphne was there a perceptibly longer penetration 
time after dark than in the day. 
This method of experimentation upon living plants in the field, 
which gives results so very quickly, leads to the view that stomatal 
movements and variations of the rate of transpiration are to a high 
degree independent of each other. Light is the fundamental cause 
for change in the first and the evaporating power of the air in the 
latter. The fact that the maximum evaporating power of the air 
occurs during the period of light does not necessarily mean that the 
stomates regulate transpiration. It has been shown that tran- 
spiration can change independently of stomatal movement (LLoyD 
32). Brown and EscomBe (53) have shown that the outward 
diffusion of water vapor observed is not as great as the capacity of 
the stomates will permit. The check in transpiration during the 
day comes with decline of the evaporating power of the air, and 
the stomates begin to close soon after, with the diminishing light 
intensity. There is no doubt that closed stomates retard water 
loss, and that stomatal movements and transpiration changes 
often occur in conjunction; but that is not proof that one is the 
cause and the other its effect. 
Conclusions 
Water loss was demonstrated in every plant experimented with 
during the winter as well as during the summer. During the low 
temperatures of winter this water loss was very low, although it 
continued to take place even wher the water was frozen around the 
stem. Either this water loss was a permanent drain on the water 
content of the stem or, as the experiments on conduction showed, 
there was a certain amount of renewal from the external frozen 
solution. Whether a plant can obtain water directly from an ice 
surface is not known, but it has been shown by Kosarorr (25) 
and others that plant roots can absorb water vapor when the 
temperature is below freezing. The amounts, though small, are 
