498 ANDREWS: PROTOPLASMIC STREAMING IN Mucor 
It is hardly possible, even if a reverse movement did take place 
along the wall during the streaming, that it would be sufficiently 
active to account for the return of the protoplasm. The streaming 
occurs first in one direction, and when the factor that has caused 
this subsides or is overcome, it streams back in the opposite 
direction. 
Streaming may be easily induced in Mucor and be caused to 
continue in first one direction and then the other without apparent 
harm to the plant for an indefinite time. This and other facts 
tend to show that it is not a “pathogenic” state of affairs as 
Keller* seems to think. The streaming may be of use in the long 
cells of these fungal filaments, as de Vriest suggests, to transfer 
substances. This, however, would not hold true for small cells 
as Ewartt has shown, for in such cases diffusion would distribute 
substances more rapidly than streaming. 
SUMMARY 
The foregoing experiments have proved the following points, 
most of which confirm Schréter’s work, but some show his work 
in a few places to be incorrect: 
1. The kind of nutrient media is of great importance for the 
proper growth of these fungi. 
2. Streaming is caused in many cases by transpiration, and 
streaming is strong or weak according to the intensity of the 
transpiration. 
3. Streaming is also caused in many cases by osmosis, as by 
the use of sugar. The streaming is always to the sugar. The 
rapidity of streaming depends on the concentration of the sugar 
solution. ‘ 
4. During streaming caused by osmosis there is no periph- 
eral streaming or movement in the opposite direction, as stated 
and figured by Schréter. This also confirms the statement of 
Ternetz. 
5. Injury, as stated by Schréter, does not produce or accelerate 
* Keller, J., cited from Pfeffer, loc. cit. 2: 818. 1905. 
ft De Vries, Bot. Zeit. 45: 1. 
. 40. 
t Ewart, A. J. On the ascent of sap in trees. Phil. Trans. Royal Soc 
1905, quoted from Pfeffer, Phys. Pl. (Eng. Transl.) 3: 359. 1905. 
