112 
William Seifriz 
between the protoplast (the plasma-membrane) and the cell wall 
(probably the colloidal aqueous solution with which the cellulose 
wall is permeated). But a uniform reduction in the tension existing 
between the surface of a flowing liquid and the walls of the containing 
vessel would not alter the rate of flow. 
There is another force a reduction of which might affect the rate 
of flow, namely, intrinsic pressure (the internal molecular force of 
cohesion). That a change in intrinsic pressure takes place with a 
change in osmotic value due to alterations in the chemical composition 
of the cell is inevitable. Decreased intrinsic pressure would probably 
mean a more rapid flow. But any statement as to the extent to which 
a change in the intrinsic pressure of protoplasm would affect the rate 
of streaming would be purely conjectural. 
Streaming in protoplasm is generally regarded as a mass move¬ 
ment of the protoplasm in toto. When viewed through an oil- 
immersion lens the appearance of flowing protoplasm in Elodea cells 
is that of a moving rope of viscous substance. It is possible, however, 
that the flow may be a movement of protoplasmic particles (colloidal 
and microscopic) in a quiescent basic medium, i.e. a phenomenon 
comparable to cataphoresis. The one-way streaming in Mucor (bread- 
mould) very markedly resembles the phenomenon of cataphoresis. If 
the streaming of protoplasm is some such electrical phenomenon 
then an increase in the surface charge of the protoplasmic particles 
would possibly result in an increase of streaming. 
That three of the four substances which arouse streaming are 
possessed of electrical properties suggests that the stimulation is an 
electrical phenomenon. Just what part the non-electrolyte alcohol 
would play in this scheme it is difficult to say, although it is evident 
that alcohol, and all the reagents which bring about marked changes 
in permeability and consequent reduction in concentration of the 
cell contents, must cause pronounced disturbances in the normal 
electrical state of the cell. 
These hypotheses of the possible causes of stimulation to proto¬ 
plasmic streaming are purely speculative. It is not the intention of 
the writer to support any one of them, but rather io indicate their 
weakness. Until we know something of the physics of protoplasmic 
streaming we cannot hope to say much on the possible causes of a 
stimulation to streaming. 
Botany Department, 
King’s College, London. 
