Cytology and Movements of the Cyanophycee. 309 
of the indigo would take place on both sides of the trichome 
towards the middle where the coloring material is heaped 
up in balls, or that this movement would sometimes pass 
from the middle to both ends. There must take place, more- 
over, in Oscillaria an extensive secretion of slimy material, 
since the particles of indigo that are shoved together remain 
thus cemented in heaps for a long time.” It will thus be 
seen that von Siebold considered that Oscillaria moved 
forward by means of endosmotic and exosmotic currents, 
the substance excreted being of a more or less slimy con- 
sistence, and helping to push the organism along. This is 
quite similar to H. L. Smith’s (73) observations of gran- 
ules streaming away from the frustules of Diatoms and 
propelling them forward quite like the means of locomotion 
of some parasitic infusoria. 
Otto Miller (56) considered that protoplasmic currents 
passed through the raphe of the diatom cell wall, receiving 
thereby a spiral motion which caused them to act as a sort 
of propeller to the organism. In answering the claim of 
Miiller, Lauterborn (46) strongly combated his views, claim- 
ing that the impinging of the spiral currents of proto- 
plasm against the water would not be sufficient to cause the 
plant to move, and he would not base a theory of this kind 
upon theoretical grounds alone, which he claimed that Mul- 
ler evidently did, for no one has ever seen protoplasm issu- 
ing from the raphe of diatoms. Muller was able to demon- 
strate that the plants could swim about when free from 
contact with any substratum. 
The osmotic theory was defended by Kozlowski (43), 
who built up a very novel theory of phototaxis. He claimed 
that a difference in the amount of light influenced the two 
ends of a frustule. Thereby different rates of assimilation 
were set up, which caused the osmotic currents and motion. 
He based these observations upon the action of the organism 
towards the source of light as it came through the micro- 
scope. But unless he could demonstrate that there was no 
