228 Knight . — The hit err elutions of Stomatal Aperture , 
In the experiments given in the tables below the weighing of the plant 
and the reading of the potometer were in each case made one and a half 
minutes earlier than the weighing of the atmometer, so that the periods 
represented by the numbers for transpiration and absorption fell one and a 
half minutes earlier than those represented by the numbers for atmometer 
loss, although the tables and figures show the respective periods as co- 
incident. 
T 
The numbers in the column — are proportional to, not equal to, 
E 
‘ relative transpiration *, since they are not calculated for unit areas. 
The numbers in the last column, ‘ Stomatal aperture *, are obtained 
from the square roots of the reciprocals of the time readings of the poro- 
meter. 
Table I. 
Plant . — Stomata. 
Half-hour 
Atmometer 
Transpira- 
Absorption 
Time. 
Stomatal 
periods 
loss in 
tion in 
in mg. 
aperture . 
ending 
mg. (E). 
mg. (7> 
10.25 
a.m. 
257 
io .33 
it 
257 
10.48 
t> 
260 
2.58 
10.55 
tt 
264 
11.30: 
i.m. 
400 
1030 
990 
11. 15 
i) 
265 
11.25 
tt 
269 
1 1.40 
tt 
276 
12 noon 
4 2 5 
1270 
IIIO 
2-99 
n -55 
tt 
300 
12.10; 
p.m. 
34 i 
12.17 
a 
345 
1680 
3-86 
12.25 
it 
298 
12.30; 
p.m. 
435 
1230 
12.35 
a 
254 
1 2 -45 
it 
245 
12.55 
it 
243 
1.0 
» 
430 
1340 
1100 
3 ‘ 12 
1-5 
tt 
240 
1. 12 
a 
239 
1.25 
it 
239 
1.30 
a 
420 
930 
950 
2*21 
1-35 
a 
249 
1-45 
tt 
243 
830 
1-55 
a 
232 
2.0 
)> 
420 
1050 
2*50 
2.10 
it 
231 
f 
2.15 
it 
234 
850 
2*oS 
2.20 
it 
234 
2.30 
a 
490 
1020 
2.25 
ii 
232 
2.40 
a 
227 
1*84 
2.55 
tt 
227 
3.0 
» 
490 
900 
790 
3* IQ 
a 
226 
830 
1*82 
3.25 
a 
223 
3.30 
tt 
455 
740 
3-45 
it 
222 
I-6 9 
3-55 
tt 
222 
4.O 
t* 
4 i 5 
700 
710 
4.10 
tt 
223 
620 
4.25 
tt 
225 
4.3O 
a 
360 
650 
1*72 
620 
4-55 
tt 
219 
5 -o 
a 
300 
5 °° 
1*67 
Total 
11870 
10570 
Decrease of water-content of the plant, 1,300 mg. 
