310 Phillips on a Comparative Study of the 
motion in the diatom in its natural surroundings, or that 
the intensity of the light would differ appreciably after pass- 
ing a distance of half the length of a diatom, one can 
scarcely see the relation of his observations to organisms 
as they occur in nature. 
Borzi (6) concluded that in general the mechanism of 
the movements of Oscillaria cannot be explained. “It only 
takes place,” he said, “in this organism when the plant is 
not multiplying, and as soon as multiplication begins, the 
filaments come to rest, and the sheath becomes much 
thicker.” He demonstrated a continuity of the protoplasm 
from cell to cell through a pore in the transverse wall, and 
this assisted the plant to correlate its movements. Neither 
isolated cells nor any form of the Cyanophyceze that have 
heterocysts were capable of movement according to his 
observations. He was also led back by the different move- 
ments of Oscillaria, to accepting a helicoid movement of 
the filament due to heat, light, etc. 
F. Cohn (15) considered that Oscillaria required a solid 
substratum to glide over. Without this they could not move. 
He based his conclusions upon their power to spread over 
the sides of the glass vessel in which they were being culti- 
vated, and even to rise above the surface of the water. He 
never found Oscillaria filaments swimming freely in the 
water. They generally used other filaments as supports 
when they could not reach other substrata. “In Beggiatoa,” 
he said, “there are short waves of contraction which run 
over the filaments, and set them in a kind of peristaltic 
motion.” These peristaltic contractions “are seen until they 
cease by the death of the filament.” This is quite similar 
to what De Bary (20) has described for germinating Cylin- 
drospermum, while Zukal (101) saw wrinkles on the sides 
of Oscillaria as it swayed backwards and forwards. Cohn 
then continued : “According to these observations it cannot 
be doubted that within Beggiatoa and the Oscillarieze in 
general, there is a contractibility which is made manifest 
