626 
N. H. SWELLEXGREBEL, 
brane is formed, which becomes afterwards closed. The 
central body divides by simple fissure, chromosome-like 
masses of chromatin not being found as is the case in other 
Cyanophycete (Kohl, Guilliermond). 
Often it can be observed that the central body loses more 
and more its ordinary shape. It becomes elongated with 
more or less developed ramifications ; often a slight curvature 
or zigzag form is to be observed (PI. 32, figs. 2, 6, 7, 8 c), 
After carefully staining, one can always observe that the 
central body is normally formed by its two components, the 
chromatin and the chi’omatic substratum. In other specimens, 
however, the distinction between cytoplasma and achromatic 
substratum becomes more and more indistinct, and it is 
impossible at last to trace a distinction between the two 
(PI. 32, figs. 8 d, e, 9). The chromatin is in such cases spread 
diffusely throughout the whole cell. The protoplasma of the 
latter is built after the ordinary pattern. The cells resemble 
very much those of some sporogenic bacteria, i*ecently de- 
scribed by Guilliermond.' 
The dissolution of the central body described here was also 
observed by Guilliermond (loc. cit.) in Scytonema cin- 
cinnatum,but it occurred there only in old vacuolated cells, 
so it is highly probable that the dissolution was of a patho- 
logic origin. This, however, cannot be the case in Calo- 
thrix fusca, as very young cells (at the ends of young cell- 
filaments) show already this phenomenon (PI. 32, fig. 8). In 
grown-up cells there appear in the cytoplasma large hyaline 
granules. They surround the central body at first, and 
seem afterwards to invade the latter, so causing its dissolu- 
tion. I was at first deluded by this phenomenon, thinking 
that the dissolution of the centi’al body had a purely mecha- 
nical cause, due to an auto-destruction by the formation of 
the hyaline granules. But a closer observation made clear 
that the diffusion of chromatin is equally found in cells which 
are not provided with hyaline granules (PI. 32, figs. 8, 9), so 
Guilliermond, ‘ Arch. f. Prot. kunde,’ 1908. 
