282 BOTANICAL GAZETTE [ocToBER 4 
while to give the values obtained for moist-air leaves of some of 
them. 
‘TRANSPIRATION OF I00 SQ. CM. OF LEAF IN AN HOUR 
Plant ite ces go i a Pager ti 
Cucumis? 5 20 34 1485 
Lupinus....... "21.67 43 3596 
Nicotiana..... QE.tt 50 or less Ig50 
Phaseolus. .... 26.11 2 1647 
napis 22.22 28 2135 
Summarizing the results obtained from the transpiration measure- 
ments,’ it may be said that: 
_1. As a result of being grown in a highly humid atmosphere, all 
the plants studied acquire a much greater than normal capacity for 
transpiration in a moderately dry atmosphere. 
2. Different families and different genera of the same family 
vary greatly in their capacity to acquire by such culture a tendency 
to extremely rapid transpiration. 
3. The transpiration ratios, for the same species, become notably 
greater as the leaf becomes fully developed. 
4. The transpiration ratios are not necessarily greater when the 7 
relative humidity of the air, during the period when transpiration 15 
measured, is very low than when it has a medium value. 
CAMBRIDGE, Mass. 
7 Not nearly all of these results have been tabulated in the preceding pages- 
