486 ANDREWS: PROTOPLASMIC STREAMING IN Mucor 
filaments and in some instances a breaking of them, allowing the 
contents more or less completely to escape. By adding the sugar 
solution first to one end and then to the other, of a filament or a 
mass of them, and washing away the sugar after each application 
before reapplying it to the opposite end, the protoplasm may be 
made to stream to the sugar at each new application. If the 
sugar solution is applied to one side, movement occurs in that 
direction and then stops as above mentioned. If then the sugar 
solution is washed away with pure water, the part of the filament 
toward which streaming occurs will take up water, and streaming 
will take place away from this part for a time, or until equilibrium 
has been established. After stoppage in this way, the addition 
of even a weak solution of sugar at the part toward which streaming 
Was moving causes it to recommence in this direction. 
The following experiment will show the effect of sugar and give 
an idea of the number of times streaming may be induced and the 
duration of each period of streaming. To do this a glass slide was 
supported at each end on a glass block in a petri dish, the latter to 
hold the liquids that ran from the slide. The spores of Mucor 
Mucedo and M. stolonifer were grown in a very small drop of 
gelatin. Two wet strips of filter paper were so arranged that the 
edge of each just touched the edge of the cover glass and their ends 
hung down some distance into the petri dish. On one of the 
strips of filter paper was placed a lump of cane sugar, which was 
renewed as fast as necessary. As soon as the sugar was moistened 
and the solution passed under the cover glass, streaming to the 
sugar began at once. When streaming ceased, drops of water 
were added to the other strip of filter paper, which washed wer 
the sugar solution, causing streaming in the reverse direction. 
The velocity of streaming in this experiment, especially toward 
the sugar solution formed in this case by the dissolving lump, 
varied. This was due to the unequal solubility of the sugar under 
the conditions here presented, which caused the solution to host 
in concentration. At other times the sugar solution did not ire 
or pass under the cover glass with equal rapidity, owing tot ; 
fact that it was impossible more than approximately to a 
the amount of water supplied to or removed from the specimen. 
: : ; d the 
The number of times this experiment was performed an 
