1 72 Murray and Boodle . — On the 
solved into fibrillae by the action of sulphuric acid. The 
cell-wall in the older parts of the filaments is very much 
thickened, and in optical section shows numerous layers of 
stratification without the use of a reagent. This thickening 
frequently goes so far as to nearly obliterate the lumen, and 
sometimes this actually happens (Fig. 8). 
Areschoug figures what he regards as zoospores germinating 
in situ in a terminal cell. We have observed an appearance 
which must be a later stage of the process. Here two inter- 
calary cells, which are about twice their diameter in length, 
are filled with a densely packed mass of tubular cells with 
delicate walls, containing chlorophyll. Owing to the crowding 
of the mass it could not be distinctly resolved, but it appeared 
to consist of rather elongated and interwoven 
tubes. Possibly a small colony of tubes is 
formed by the division of the contents into 
zoospores, which germinate inside the mother- 
cell, and increase in size until they burst 
it. Zanardini mentions terminal and other 
coniocysts. We are not quite sure what he 
does mean, but on lateral branches globular 
terminal cells occur here and there which 
may possibly have a reproductive function. 
The appearance however which we venture 
to think possesses special interest is pre- 
_ sented by the groups of siliceous spicules 
Fig. 1 1 . Filament of ' & r r 
Spongocladia vauche- which plentifully strew the course of the 
sp?OTkfTft* S Ares e - tubes - These were noted by Areschoug, 
choug.) and also the further fact that the grey 
compact appearance of the apical portions of the branches 
is owing to the dense occurrence of these (obviously) sponge- 
spicules — which moreover cause the whole thallus to feel 
hard to the touch — like a fresh sponge in short. Areschoug 
does not appear to have satisfied himself as to the origin 
of these spicules beyond supposing that they belong to 
a sponge. They are manifestly far more abundant than is 
consistent with a merely accidental presence. Mr. Kirkpatrick 
