ANDREWS: PROTOPLASMIC STREAMING IN Mucor 493 
to this same point. Schréter has shown that light may cause or 
accelerate streaming, and I can confirm his observations on Mucor 
stolonifer, which he used, and also on M. Mucedo. These remarks 
refer to light of moderate intensity, for the light may be too strong 
for streaming to occur. 
My experiments were carried out partly in daylight and dark- 
ness alternated and partly in gas light. In the first case the 
investigations were made by means of the freezing-apparatus of 
Molisch. With this arrangement the specimens could easily be 
kept at the desired temperature by means of warm or cold water 
siphoned in and out and the observation be carried on directly in 
the laboratory under the influence of light or dark. On heating 
the apparatus to the optimum temperature the specimens were 
kept first in the dark for two hours, when the protoplasm ceased 
to move. On admitting light a slow streaming began in five 
minutes and after a time became as rapid as the streaming of 
the control specimen. This experiment was repeated several times 
with the same specimen and always with the same result. When 
the temperature of the specimens was lowered from the optimum 
to 17° C. and then to 14° C., and the experiment repeated other- 
Wise the same, the streaming became slower and slower on each 
new admission of light. Also, when the temperature was raised 
above the optimum but slightly (28° C.), the streaming on admit- 
ting light showed a rapid decrease in velocity. Too great heat or 
too intense light can readily, especially the former, make the 
Protoplasm non-responsive. If, however, these are not con- 
tinued too long the protoplasm of these fungi will recover in from 
one-fourth to one hour and stream as actively as before. 
In the experiments made with the gas light an ordinary Wels- 
bach burner was used and the investigations carried out in daylight 
and darkness repeated. The same results were obtained. In both 
of these series of experiments the specimens were preserved for 
24 hours to see if in all cases they would become normal as com- 
Pared to the controls for activity of streaming. At the end of this 
time both the specimens experimented on and the controls were 
normal and equally active. 
