96 BOTANICAL GAZETTE [AUGUST 
noted for series Ia. For Id, the drop really begins on the 12th hour 
and falls from 1.00 to 0.69, giving a difference of 0.31; for Id, 
the fall is from 1.00 to 0.59, giving a difference of 0.41. The 
recovery for Ib, is from 0.69 to 0.93, and for Ib, is from 0.59 to 
0.85. The difference value is 0.24 in one case and o.26 in the 
other. It was pointed out for series Ia that the recovery of the 
older leaf is more marked than that of the younger leaf. This 
E|? 
Tb: 1000 \ ae 
938] Al; [ 
SoM, 
813] INDEX OF FOLIAR TRANSPIRING POWER 
Sear 
Bie 
150] 188} a 
*, 
x 
100] 125 ae a 
os cape EVAPORATION at 
Oe oe lewwachosassptoretes i 
tS jaty 2916 . Tidy > 7 om Ps BNE | IB Bs ese 5 BERS 
Fic. 3 
feature is again borne out in the present series, where the values 
for Ib; are in excess of those of Id,. 
For the reason that the leaves of series Id, are very nearly of the 
same age, the same variation as set forth in the previous season 
will not be in evidence. The minimum values are slightly lower. 
As a result the ratios between maxima and minima are respec- 
tively 2.19 and 2.27. The same high foliar transpiring power is 
present at the 17th hour. This agrees with the former series. 
The data submitted in table V give the march of foliar transpiring 
power during the process of wilting from July 24—August 7. 
