ANDREWS: PROTOPLASMIC STREAMING IN Mucor 471 
a slow-growing one or one without branches. Especially is this 
true in the case of an unbranched filament where the transpiration 
is influenced by artificial means. The sudden action of very dry 
air, for example, has a much more noticeable effect in producing 
streaming in the branched filament with large exposure surface, 
by the rapid withdrawal of water, than in the single unbranched 
filament with a much smaller exposed surface, in which streaming 
has just begun or in which it can for the first time be produced. 
The difference in the character of the cell walls of the branched 
and the unbranched filaments as to transpiration is unimportant 
in this connection. In unbranched filaments it is possible to 
cause streaming by artificial means before it would normally occur. 
The two previous experiments show that a streaming of the 
protoplasm may be easily produced by artificial means. The 
artificial means in the instances just cited was transpiration. They 
also show that as transpiration is active or inactive, streaming is 
active or suppressed. The filaments grow when completely sub- 
merged, but the growth is not so rapid in wholly as in partly 
submerged fungal filaments. 
In order to ascertain if streaming could occur in a saturated 
atmosphere, glass ring cells were made and the spores of Phy- 
comyces nitens grown in the suspended 5 per cent solution of cane 
Sugar. The filaments grew at the optimum temperature out of 
the solution into the completely saturated air of the closed cell, 
and when observed 48 hours later no streaming was present. In 
another cell similarly arranged the cover glass was slightly raised 
after the filaments had grown 48 hours. Streaming began in a 
few minutes and was very evident. This last arrangement allowed 
@ slight interchange between the air of the artificial cell and the 
drier air of the room; and this small difference was sufficient 
‘0 cause a rapid movement in the second experiment, and at the 
same time showed that while the change in humidity was slight, 
a little change in this respect may produce a considerable increase 
I transpiration and consequently a decided acceleration in proto- 
Plasmic streaming. The same experiments with the same results 
Were carried out with Mucor stolonifer and M. Mucedo. The move- 
ments of the protoplasm shown by these experiments were there- 
°re induced wholly by the transpiration occurring in that part 
