ANDREWS: PROTOPLASMIC STREAMING IN Mucor 473 
librium was again practically established. Or if other parts were 
then exposed to the air the direction of motion was to them. In 
all cases excessive and prolonged transpiration in the ways indi- 
cated must be avoided to prevent a fatal termination. If this be 
done and care used, the number of times the protoplasm may be 
caused to stream to a transpiring part or away from what was a 
transpiring part, is unlimited. These experiments show, therefore, 
that transpiration causes streaming under the conditions here 
mentioned. 
The dependence of protoplasmic movement on transpiration 
in the cases here referred to was further proved by growing the 
spores of the fungi mentioned, on the under side of a cover glass 
of an ordinary metal or glass gas chamber. Under these condi- 
tions, when saturated air was drawn through, the protoplasm did 
hot stream in those filaments protruding into the saturated air. 
When, however, air that was nearly saturated was drawn through, 
slow streaming began. When very dry air was drawn through the 
gas chamber after the filaments had been in saturated air, stream- 
ing instantly began with great rapidity; and if this dry air was 
drawn through very long, the filaments were soon dried out and 
the exposed parts killed. The streaming finally stopped in those 
filaments in which it had been caused by dry air. When this 
occurred streaming was again produced by admitting air that is 
somewhat drier than that used to induce streaming before, if one 
does not delay too long before admitting the air. If after the use 
of the several degrees of dryness of dry air to induce streaming 
one readmits moist air in different degrees of humidity, streaming 
tom the exposed parts of the filaments takes place for a time 
with a velocity in accordance with the humidity of the surround- 
ing air. This movement continues till equilibrium is established, 
the time for which, however, will vary. The return streaming 
movement is slower and continues longer if the air is only partly 
made moist than if the air is saturated. 
THE INFLUENCE OF HYDROGEN 
In the filaments of Mucor Mucedo and M. stolonifer, grown 
as above described, hydrogen stopped the movement of the pro- 
‘oplasm in 20 minutes in moist air. Schrdter gives about 5 
