368 Curtis: SOME OBSERVATIONS ON TRANSPIRATION 
IV. ABSENCE OF LIGHT 
6 
6A.M. 7 e249 Io Ir oo FM. 2 5 4 5 
Ficus INFLECTA, 58 71 64 52 53 96 7o 110 68 54 56 48 
Temperature, 17.5 18 18.5 
Hygrometer, 51 50 49 
FIcus ELASTICA, 286 255 247 280 294 270 265 266 247 223 203 166 
17.5 17.5 18 18 
40 41 40 39 
GARDENIA JASMINOIDES, 32 34 30 49 48 46 40 44 38 32 36 34 
Temperature, 19.5 20 19.5 20.5 2 
Aygrometer, 37 37 38 37 36 
NERIUM OLEANDER, Rt G0 67.59 83 75.64. 62 56.45 @ 
Temperature, 207/121 21 21 
Hygrometer, GO 2614s 44 44 
ACALYPHA HISPIDA, 90 88 84 68 76 85 93 119 86 78 80 84 
Temperature, 18 19 20 20 
Hygrometey, 38 37 36 36 
JUSTICIA ELEGANS, 210 190 164 135 198 167 170 195 166 174 192 213 184 
Temperature, 18 19 195 
Hygrometer, 36 36 33 
that this must lead to a disarrangement of the operation of the vital 
processes. I was particularly interested to note that the leaves in 
many cases decidedly changed their positions. They often appeared 
to flag as if from the loss of water. They were, however, perfectly 
rigid and the changed turgor tensions had caused the curvature 
of the petioles. In other instances the edges of the leaf turned 
strongly upwards. This was particularly the case in Begonia while 
in Fuchsia many of the leaves bent down, forming a half circle 
and in so rigid a leaf as that of Ficus a lateral twisting of the 
leaves was sometimes to be seen. 
The amount of water transpired is rather surprising in view of 
the fact that we usually consider the stomata as closed in the dark. 
Very few authors have maintained that the contrary condition ' 
the case. Considering the ratios that have been found by Garrea® 
and others between the dorsal and ventral surfaces of leaves it 4P° 
pears impossible that the cuticular transpiration could equal the 
volume recorded inthe table. Only one instance has been noth 
where the plant seemed to have the power of closing the stomata. 
In the case of Cycas revoluta brought into the dark room at 7-45 
a.m. weighings were made hourly from 12.45 on with the ee 
lowing results : loss of 7 mg., 25, then gained for four hours 3, 
3, 2, loss 2, 7, gain 2, 4,2, 0, 2. Temp. 21 to 19, Hygt™ 3? 
