ANDREWS: PROTOPLASMIC STREAMING IN MucoR 495 
controllable by the experimenter. Nor-can I agree to Schréter’s* 
idea that streaming can be induced only in branched hyphae. I 
have caused streaming to occur in the filaments of Mucor stolonifer 
and M. Mucedo when unbranched as in FIG. 6, 7, and 8, when they 
were put under the optimum conditions of temperature, etc. 
Also, as stated heretofore, I have induced streaming in such un- 
branched filaments by osmosis and transpiration. 
The filaments of M. stolonifer are not always filled with granular 
protoplasm before branching, as Schréter seems to think. In 
those cases where this is not the case streaming may easily occur. 
I performed some of my experiments of this kind in room tempera- 
ture varying from 16° to 19° C., where fairly rapid streaming 
occurred, but it was noticeably slower than at the optimum 
temperature. 
As also mentioned above, a sudden change almost immediately 
caused streaming. When a specimen whose protoplasm was still, 
but in a condition to stream, was suddenly cooled from 23° to 
16° C. streaming was induced, or if heated from 16° to 19° C. or 
from 23° to 26° C. streaming was generally produced. 
The movements of the protoplasm in the hyphae of several 
filamentous fungi have been described by Arthur, Ternetz,t and 
Schriter.§ In Mucor stolonifer and M. Mucedo, both of which I 
have studied, the streaming shows no difference, so that my re- 
marks on this point apply equally well to both. Fic. 9 shows a 
Portion of one filament of M. stolonifer grown in a sugar solution. 
It was found that the rate of growth of these fungi, their size, and 
branching frequently varied greatly although grown under the 
same conditions. The streaming also showed a great difference 
as to velocity. Sometimes it was so slow as to be scarcely dis- 
cernible, as for example when osmosis or transpiration was very 
feeble. On the other hand, streaming was fast or very rapid 
according as some factor such as those just mentioned was active. 
n those filaments that had attained some length numerous 
vacuoles were generally present, and these varied greatly in size 
Cin a teas 
