504 Arthur . — The Movement of 
a species much given to the early formation of cross-walls in 
the hyphae, was grown upon neutral nutritive gelatin. This 
species branches acropetally in a most uniform manner, the 
branches making an angle of about sixty degrees with the 
main axis, and both growing quite straight. The advancing 
hyphae all remained appressed to the moist substratum, giving 
a regular featherlike appearance. On the second day move- 
ment was to be seen. At this time the central part of the 
mycelium bore plenty of sporangiophores, and was further- 
more much septated. The protoplasm was crowded with 
vacuoles, but quite free from granules. The movement was 
not especially lively ; in all cases it proceeded toward the 
growing apex, and although the whole branch-system was in 
normal growing condition, the stream mostly kept to the 
main axial hypha, only now and then entering a side branch. 
On the day following the movement still continued in the 
same direction. In two cases I was able to trace the stream 
back from the growing apex into the central mass of mycelium 
until a cross-wall was reached where all movement ceased. In 
these cases the whole length of the effective hypha was in 
contact with the moist substratum, although the proximal 
end was overlaid with growing mycelium, while the distal 
end, into which the stream poured, was both extending and 
half exposed to the air. I assume that in this case the 
small difference in osmotic conditions between the two ends 
of the active hyphae was the cause of the sluggishness of the 
current. 
In another case still more uniform osmotic conditions were 
secured. Spores of Rhizopus elegans were grown in bread- 
broth entirely submerged. On the fifth day neither vacuoles 
nor movement were yet to be seen. On the tenth day vacuoles 
were abundant, and two or three instances of faint streaming 
were detected, but the development was no longer entirely 
beneath the surface, for a few sporangiophores had risen into 
the air. 
In the last case another phenomenon of protoplasmic move- 
ment appeared, which had also been seen a number of times 
