1312 
the period of rest, a much larger amplitude is to be noticed, than 
in the case of uninterrupted recording, which proves the necessity 
Thursday, October 21st 1920. Friday, October 22nd, 
Peperomia maculosa 
' 
7106 Sa eM roel. Wee ES A EY Ge OG 19 Oi HEN Tora Soh eS." Gk 7 eke 
MRE ot DOC IE SES es EEE ae AREER Se ERE: wa fer A 
| bi dohakekodetestel | i} 1] I 
EE 
sf 
Ficus elastica 
Fig. 3. Course of the stomatal aperture in leaves of Peperomia maculosa 
and Ficus elastica recorded simultaneously with intervals of 20 minutes for 
nearly 26 hours. The lengths of the lines denote the time, in which the 
pressure in the porometer is increased from 7 to 4 cms. of water below the 
height of the barometer. 
of the period of rest (ep. fig. 2 and fig. 3). If from 13 to 14 May 
the rate of time between “most open” and “most closed” was 1: 16, 
in fig. 3 it is 1:85. It is also remarkable, that even during the 
night opening and closing may be noticed, which proves, that other 
factors than light act a part. 
Comparison between Ficus and Peperomia shows, how with the 
latter the stomata check the current of air but very little in the 
middle of the day, towards evening the closure is much quicker 
with Ficus. What lasts still 5'/, min. at 4 o’clock, is done in 125 min. 
between 5 and 7 o'clock. In the evening Peperomia gave a slower 
closure than Ficus, in the morning however an opening at least 
equally quick. The ratio of open and closed is particularly strong 
in the case of Peperomia. At one o’clock in the afternoon the period 
of fall is not yet '/, minute, about midnight 32 minutes. Here it is 
not the place for a further inquiry into these results, which immediately 
tempt to further physiological contemplations. 
