628 
N. H. SWELLBNGREBEL. 
The stages with diffuse chromatin resemble very much the 
Bacteria with chromatic granules spread throughout the pro- 
toplasma. There is not yet differentiation between cytoplasma 
and nuclear plasma. Other forms of Bacteria, with their 
chromatin condensed into a more or less compact central mass 
(Sphaerotilus [SwellengrebeP], Bac. spirogyra [Dobell^]), 
find their match in those forms of Calothrix f usca, where a 
well-marked differentiation between cytoplasma and nuclear 
plasma does not yet exist, but where the chromatin is no 
longer spread throughout the whole cell, but takes a central 
position (PI. 32, fig. 8 c). The stage with a well developed 
central body is not yet found in the group of Bacteria. 
Biitschli (loc. cit.) has already observed the resemblance of 
the structure of Cyanophycem and larger Bacteria, the latter 
showing a central agglomeration of chromatin suggesting a 
central body. I think that the stages with diffuse chromatin 
come much nearer to the structures described in Bacteria, 
and that these observations may aid to support the view con- 
cerning the relationship between Cyanophyceffi and Bacteria. 
Hygienic Institute, 
Amsterdam ; 
June, 1909. 
EXPLANATION OF PLATE 32, 
Illustrating Dr. N. H. Swellengrebel’s paper “ Note on 
the Cytology of Calothrix fusca.” 
(Drawings made under a Zeiss 2 mm. homog. oil immersion apochromatic 
comp. 6c. 18.) 
Figs. 1 — 9. — Sections from 4 — 6 n thick. 
Figs. 1 and 3. — Three cells showing a well-developed central body with 
differentiation into chromatin and achromatic substratum. 
* Swellengrebel, ‘ C. R. Soc. de biol.,’ Juin, 1908. 
“ C. C. Dobell, ‘Quart. Journ. Micros. Science,’ vol. 53, May, 1909. 
