582 C. CLIFFORD DOBELL. 
cell [cf. Zettnow (1908), Holling (1907), Guilliermond (1908), 
te., and text-fig. A(3)]. That this is so in the case of 
B. spirogyra I cannot admit, nor, indeed, would anyone 
who had seen my preparations. I have already shown these 
to a number of persons, all of whom agree that such an inter- 
pretation is impossible. Not only are the varying disposition 
of the filament and its remarkable distinctness entirely against 
such an interpretation, but the appearance of burst forms 
(Pl. 18, figs. 4, 5) conclusively proves that the filament is a 
Tax mrG.. AL 
ile (2x6 3. 
B. spirogyra (1), Sp. giganteum (2, 3),—2, after Swellen- 
grebel (1907); 3, after Guilliermond (1908). In B. spirogyra 
there is a simple filament. In Sp. giganteum there is 
(according to Swellengrebel), a kind of irregular rodded spiral 
filament: according to Guilliermond the ‘filament is falsely 
suggested by the arrangement of granules and cytoplasmic 
alveoli (3). The alveoli are, however, ‘clearly shown by Swellen- 
erebel (2) together with the filamentar structures. 
solid body independent of the protoplasmic alveoli. In all 
carefully fixed and stained preparations the filament is as 
unmistakable as the nucleus of any other cell. In the case of 
Sp. giganteum, moreover, Swellengrebel has published 
figures which show both the filaments and the cytoplasmic 
alveoli in the same cell (see text-fig. A [2]). 
I may add that I have been able to demonstrate the exist- 
