B. Faluuila Form. — The palmella cells are spherical, or quite 

 often two, three or four cells make a sphere. The walls are thick 

 compared with those of the filament. No vacuoles are found in 

 the protoplasm. The chloro{)h)ll f^ranules are much larj^^er than 

 those found in the filament. In size and other characters of the 

 nucleus one cannot find any difference between the two forms. 

 Palmella cells have much larf^er pyrenoids than the filaments. 



The palmella cells can be directly transformed into the filament 

 by thinniuL,^ of the walls, acquiring of the vacuoles, etc. In 

 several cases, therefore, the intermediate forms are found. 



The palmella form, being put into the weaker solution, usually 

 produces zoospores, two or four in a cell or sometimes as many 

 as eight. The zoospore has two flagella and a red eye-spot. 

 The spores after swimming for a while acquire a firm wall or shell. 

 Voung filaments, even as late as the three-celled stage, often 

 carry the empty shell at one end. 



III. Conclusion 



Recapitulating the differences : the filamentous form of Stige- 

 oclonitini has thinner wall, central vacuole, smaller chlorophyll 

 granules, and smaller pyrenoids, whereas the opposite prevails 

 in the palmella cells. These cytological characters change, as 

 Livingston states, if one form is transferred from one solution into 

 another of different strength. Mow the solution acts upon the 

 cells I do not know. It is however certain that these compli- 

 cated structural changes cannot be accounted for simply as phys- 

 ico-chemical action of the solution just as would be the case on 

 an inorganic body. Livingston cites a case in which a dead cell 

 changed its form, when transferred into a solution of different 

 strength. The form change which constitutes a part of the above 

 complicated modification may be due to the osmotic action, but 

 we cannot at all explain from physical point of view how the 

 thickening of the cell-wall, enlargement of the pyrenoid, etc., 

 are brought about. 



It is not an easy matter to find out whether or not the adapta- 

 tion in this case is purposive. It seems to me however, that the 

 increase of the thickness of cell wall and the enlargement of the 



