474 ANDREWS: PROTOPLASMIC STREAMING IN MUCOR 
minutes as the time required, but this seems a little too short a 
time in view of the average of 20 minutes which I found from 
experimentation with a large number of fresh plants. After 
streaming had been stopped by hydrogen it began again in one 
minute after fresh air had been readmitted. This experiment 
was repeated many times on the same filaments, always with the 
same effect. The streaming had in each case again become visible, 
but the effects had not entirely disappeared, as it responded less 
- quickly after many trials. 
Fresh specimens of Mucor stolonifer and M. Mucedo were not 
affected so soon by hydrogen passed through in moderately dry 
air as in saturated air. For example, it required pure hydrogen, 
as shown by many experiments, on the average 54 minutes to stop 
the streaming of the protoplasm in this plant in dry air. Also a 
somewhat longer time as compared to those in moist hydrogen was 
required for recovery. After streaming had been stopped in dry 
hydrogen, 5 minutes instead of 1 minute were required for 
recommencement of streaming after fresh air had been drawn 
through. 
The protoplasmic streaming of fresh specimens of Mucor stolont- 
fer and M. Mucedo was again stopped by a stream of saturat 
hydrogen in 20 minutes. When this experiment was performed 
the streaming was at first toward the base. Then, when dry 
hydrogen was passed over the specimen, the streaming began to the 
tip and continued for one-half minute. Again, moist hydrogen 
was admitted and streaming began to the base, stopping in 15 
seconds. Then dry hydrogen was passed through and streaming 
began to the tip, ceasing in 10 seconds. This experiment was 
repeated ten times with the dry and moist currents of hydroge®, 
alternating them each time, always with the same result that 
streaming was reinduced each time. The moist hydrogen was 
easily obtained by causing it to pass through G, H, and I before 
entering U’, FIG. I. 
In another series of trials like the preceding, b 
specimen, the length of time the protoplasm streame 
moist or to the dry hydrogen, respectively, is shown by 
ing experiment, TABLE III: 
ut on another 
d from the 
the follow- 
