1918] BAKKE—WILTING 107 
on December 1 at 10:30 it took 246 seconds. From that time 
until December 3 there was not much variation either at night 
or during the day. 
TABLE VII 
POROMOTER READINGS DURING PROGRESS OF WILTING OF A 
Helianthus annuus PLANT GROWING IN LABORATORY 
Rate cf evapora- | Rate of flow, time 
7 Pees tion pied standard-jinterval in seconds 
deny ap Hen scot between succes- 
sive bubbles 
Proves. $9 26200 5 oho oo osc cae ee 
OG he rk ins ae Pe Oe 
eh WO Bien 
\15:30 Pde ee es ee 
29 16:00 0.72 160 
17: 12 140 
30) 14:30 0.79 150 
2 1.34 146 
{10:30. 0.97 246 
December “ae 1.11 266 
20: 0.54 259 
10:30 i760 276 
24 14:30 E.91 260 
20: I.41 262 
3: 10:30 I.70 269 
The data of the series grown continually in the greenhouse, 
where the evaporation was very low, are given in table VIII. 
These results, which were obtained at regular intervals on 5 
Successive days (November 29 to December 3, 1917), do not show 
any marked differences. Considering the experimental error 
which would be present, there is not sufficient difference in any one 
case to indicate that stomatal movement was present. The plants 
used in this series were not watered for 3 days before the beginning 
of the experiment. 
The stomatal diffusion as cieanived by the porometer was 
also determined for plants which were grown for the same period, 
but were not subjected to any extended period of wilting. The 
general average for the stomatal diffusion as represented by the 
time interval between successive bubbles of the air intake tube 
of a porometer was found to be 1o5 seconds. No attempt was 
