276 BOTANICAL GAZETTE [OCTOBER 
greenhouse, where the relative humidity was usually not far from 
60 per cent.' 
In general the plants grown in nearly saturated air and in dry air 
or in that of moderate humidity presented considerable contrasts in 
their development.? Those from moist air were taller, more slender, 
longer-leaved, less hairy (if the plant were naturally pubescent), with 
od 
én j : as 3 >hotograpnet 
Fic. 1.—Ipomoea plants, moist-air form and dry-air form. X4- Photograt 
by Rospert CAMERON. 
. a < 3 Re 2a VES. 
thinner, lighter-colored, more pliable, and more translucent a6: 
ee ‘ selop- 
In many cases the moist-air plants showed an accelerated deve af 
. ; ‘ : sicet 1€ 
ment, producing more leaves in a given time and flowering et ‘ 
A : : eee! ae tiv 
than those in drier air. Most of the exact measurements 0! rela ; 
nr * > . y 7 Vi yar 
‘ The writer’s thanks are due to Professor GEORGE L. GOODALE of Har 
University for the use of space in the greenhouses of the university. 
2 See WIESNER, J., Forminderungen von Pflanzen bei Cultur im 
Raume und im Dunkeln. Ber. Deutsch. Bot. Gesells. 9:46-531- 1891. 
absolut feuchte? 
