Cytology and Movements of the Cyanophycece. 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 Miiller (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 Miil- 

 ler evidently did, for no one has ever seen protoplasm issu- 

 ing from the raphe of diatoms. Miiller 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 



