124 BOTANICAL GAZETTE [AUGUST 
. 
TABLE IT 
POTOMETER WEIGHINGS 
- Be Loss: os 
Time mt «(aoe per min.: Remarks 
oe g Ea e| srams gra 
4 
PAD P.M ie oes 108 .890 CGE eae erent cw on ; 
S°IG Pee eee. 108.775 24 0.115 | 0.0048 | The rate in normal air before 
the experiment : 
4:18 P.M.......| 108.625 | 68 ©.150 | 0.0022 | Includes the period — 
which the plant was inclos 
PAR POM 108.540 | 30 0.085 | 0.0028 | The rate in normal air after 
the experiment 
TABLE III 
Plant placed in cylinder 3:12 P. mu. 
Water stopped flowing from aspirator 4:13 P. M. 
Duration of experiment 61 minutes. 
Total gain in weight of P.O, tubes 0.343 grams. 
Amount of water in air used 0.217 grams. 
Net gain of P.O, tubes 0.126 grams. 
will be seen that for the first of these intervals the rate was 0.0048 
for two minutes or 0.00968"; and for the second, 0.00288 for five 
minutes or o.o140®, making a total of 0.02368". Now, 0. 1500 
— 0.0236 =0.1264; it is thus seen that the two methods check within 
0.0048" for a one hour’s run. 
It would be useless to give the details of the other two check 
experiments, since they were carried on in exactly the same manner 
and extended through approximately the same length of time. It will 
suffice simply to show the results of the three experiments, corrected 
for time, as follows: 
TABLE IV 
Transpiration | Transpiration F 
as recorded by | as shown by Difference 
potometer P,O; tubes 
RES SI Se eRe? Merges 
Ist experiment............. o.1264gm ©. 12608m o.c004e™ 
and experiment... . jas. 0.0690 °. ©.0030 
ard experiment... 3. ©.0614 0.0624 0.001! 
