Barber. — On the Structure of P achy thee a. 143 
boundary. Their colour approaches that of the spaces be- 
tween the cortical filaments, while that of the spaces between 
the oval bodies themselves is frequently similar to that of the 
Central matrix. 
At first sight the oval bodies appear to be swollen 
cells which give rise by branching to fascicles of radiating 
filaments, and there is at least one case which seems to 
support this view. In the majority of cases, however, they 
would appear to be the spaces between filaments, and they 
appear to be continued outwards into the slightly-coloured 
matrix separating the cortical filaments. There are at present 
great difficulties in the way of this latter view. The distinct 
wall separating them from the central matrix is never double ; 
and it would undoubtedly be double if the oval bodies were 
merely spaces separating filaments. Again, in the section, 
the oval bodies appear to be separated by wide spaces from 
one another ; and these spaces are bridged across by parallel 
bars distinctly continuous with the walls of the oval bodies 
(Fig. 6). The central filaments appear to wind in and out 
between these bars. It would be difficult to imagine that the 
cortical filaments suddenly lose their filamentous character 
and expand into these spaces. Finally, in the second section, 
which seems to pass at some distance from the centre, we meet 
with some of the oval bodies cut across (Fig. 7). They 
appear to be circular in section, and have a well-marked wall 
surrounding them. They are separated from each other 
by irregular spaces, and the latter show no signs of being 
formed by cells — as would be the case if the circular bodies 
represented merely the spaces between cell-filaments. 
From what has been said, it will be at once clear that 
nothing decisive has been learnt regarding the systematic 
position of the organism. That it is an alga seems to be 
now generally conceded ; and it probably grew on the sea- 
bottom, where it rolled to and fro in the passing eddies. 
The presence of transverse walls indicates that it is not 
one of the Siphoneae ; the branching appears distinctly of a 
higher order than that of the Cyanophyceae ; and the presence 
