98 BOTANICAL GAZETTE [AUGUST 
From the tabulated data of table V, and from graph (fig. 4) of 
series Ia, it is noticed that there is a marked decrease in foliar tran- 
= a 
~~; “Ww, 
Me “tay 
spiring power from July 24 
up to the time when the 
if plant wilts. The transpir- 
le ing power of leaf Ia, is 
. very irregular. There is 
2 J : no doubt but that the plant 
Beer has attained its permanent 
Vg wilting point on July 29, 
— but because the leaves of 
H i this series are somewhat 
a older than Ia,, and as they 
z tf are located nearer the ab- 
Fa sorptive center their action 
BERR will be more or less modi- 
? 7 fied by the presence of the 
a younger leaves at the tip. 
ba ‘| . For the leaf Ia, there is a 
Mol g marked decrease in the 
4p 
S 
P as 
me 
\) 
A] 
INDEX OF FOLIAR TRANSPIRING POwE 
az 
4 me 
Fe. 
*s, 
at y 
ly 24 1916 
foliar transpiring power 
from July 24 to July 309, 
the foliar transpiring power 
being especially high on 
tg eT Ge a August 1. This feature is 
Sina’ PBB ES oe probably in response to the 
(fi Fae exceedingly high tem- 
perature at that time. The 
evaporation from the 
standardized atmometer 
bears out this statement. 
From August 1 to August 7 
the index of foliar tran- 
spiring power proceeds 
almost in a straight line, 
except for small dips occur- 
ring in-the majority of 
