Tort] BRIEFER ARTICLES 3901 
the nucleus to the outer limits of the cytoplasm. They are all in prac- 
tically the same plane, and thus form a plate across the center of the 
cell in the place where the cross wall, between the daughter cells, is to 
be produced. In several of his figures OLtvE shows fibers which appear 
quite like these. The stage just described, indeed, bears a close resem- 
blance to his figs. 24-26 of Oscillatoria. However, since he does not 
describe these fibers in his text, or show them in longitudinal section, 
we cannot be sure how similar they are to those in Lyngbya. 
At the end of each fiber in Lyngbya, there is laid down, against the 
cell wall, a small granule which stains black with Haidenhain’s hema- 
toxylon. These granules increase in size until they coalesce to form 
a ring around the center of the cell. This ring marks the place where 
the cross wall is to be formed, and it can still be seen, around the edge 
of this wall, after the wall has grown completely across the cell. 
The production, at the place where the wall is to appear, of this 
ring by the fusion of granules formed at the ends of fibers which extend 
from the nucleus, would seem to indicate that the nucleus plays an 
important part in the formation of the wall, and that the nuclei of the 
Cyanophyceae may have functions similar to those of the nuclei of other 
plants. The presence of the fibers may indicate paths of conduction 
from the nucleus to the cell wall. Davrs? describes a similar relation 
between the nucleus and the formation of the blepharoplast in the spores 
of Derbesia. Here strands radiate from the nucleus to the plasma mem- 
brane in the form of a funnel. According to this writer, “granules may 
be found on these strands apparently moving outwards towards the 
plasma membrane. These numerous granules accumulate in a circle 
just underneath the plasma membrane and fuse with one another to 
form a deeply staining firm ring, which is the blepharoplast.” 
In this discussion the central body of Lyngbya has been called a 
Nucleus. This interpretation would seem to be justified by its structure 
and its relation to the formation of the cross wall. 
The writer is indebted to Professor D. S. Jounson, in whose labo- 
ratory at the Johns Hopkins University the work was carried on, for 
materia], and tor other courtesies—Witi1AM H. Brown, Michigan 
Agricultural C ollege, East Lansing, Mich. 
* Davis, B. M., Spore formation in Derbesia. Annals of Botany 22:1-20. 1908. 
