152 BOTANICAL GAZETTE [AUGUST 
in which the instruments will be exposed to absolutely parallel 
atmospheric conditions. The danger in placing too much reliance 
on a single set of data for a given locality was impressed upon 
the writer by results secured from a supplementary series of 
instruments which was operated in various plant habitats in the 
vicinity of New Haven for the last five weeks of the season. During 
this period the mean weekly evaporation rate at the central station 
averaged 86 cc. Instruments in the other sites averaged as 
follows: exposed summit of trap ridge, about 6 km. from coast, 
altitude 81 m., 138 cc.; salt marsh, 128 cc. ; lee of low sand dunes 
along shore, about too m. removed from salt marsh station, about 
131 cc.} open bog, altitude 6 m., 81cc. More accurate conclusions 
as to the evaporation intensity prevailing throughout the state 
might of course be derived from a series of instruments placed 
in diverse habitats in each of the localities selected and operated 
for several seasons, but at the present time no further investigation 
along these lines is contemplated. And while the data obtained from 
the experiments of this one season do not permit final conclusions, 
they at least suggest that the evaporation intensity of the air may 
be a factor of no little import in determining the character of the 
vegetation in different parts of Connecticut. 
YALE UNIVERSITY 
