476 BOTANICAL GAZETTE [JUNE 
water is cold, more so in the tree and shrub associations than in the 
herbaceous ones. This necessitates conservation of water and 
consequently xerophytic adaptation. Leaves that are produced 
in a time of drought (June 1912 at Mud Lake) are more xerophytic, 
in that they remain upright, than those produced under normal 
conditions (May 1912 at First Sister Lake, fig. rr). Neither obser- 
vations in the extreme summer drought of ro11 in Cheboygan 
: Pe: 
% Mah 
Fic. 11.—Chamaedaphne calyculata in bloom at First Sister Lake; May 6, 1912 
County, Michigan, nor experimentation under severer conditions 
than obtain in nature made it apparent that such a degree of xero- 
morphism as exhibited by Chamaedaphne was necessitated by the 
summer conditions alone. 
ABSORPTION OF WATER VAPOR FROM A SATURATED ATMOSPHERE 
From the increases in weight repeatedly obtained while experi- 
menting with potted plants and cuttings of ericads during times of 
high relative humidity, it seemed necessary to assume the ability 
to absorb a measurable amount of water from the water vapor in 
the air, at a time when the evaporating power of the air was low. 
During June and July 1912, some measurements were made of the 
