MEMORANDA. 117 
separating the two external valves. The areole are by no 
means very minute, being only about 15 in -001", and they 
are regularly hexagonal. The portion of the valve which 
remains entire exhibits part of a narrow transversely striated 
median line; and, arising from it, canaliculi, as in S. lata 
and fastuosa, very couspicuous at the base, but suddenly 
becoming inflated and faint. These characters are strictly 
confined to the valve; for on accurately focussing the interior 
organ, nothing whatever is perceptible but the beautiful and 
uniform areolation. On slightly changing the focus, the 
median line and canaliculi of the valve beneath are then 
shadowed through. What is this interior organ? It does 
not appear to have any intimate connexion with the valves, 
for if that were the case, some trace of so marked a structure 
would be visible by means of a strong transmitted lght. 
Like the valves, it is highly siliceous. At first sight, this 
remarkable arrangement would appear to be irreconcileable 
with the views at present entertained relative to the character 
of the Diatomaceous cell, and the process of self-division. 
I must content myself at the present moment in merely 
recording the fact, and in drawing the attention of students 
of the Diatomacee towards it. 
The larger figure is x 400. The smaller one, more highly 
magnified, represents the areolated structure. — R. 
Grevit_z, Edinburgh, Noy. 24th. 
Microscopic Hints from Australia.— I have only lately re- 
ceived the number of this Journal (No. XVI, p. 299), in 
which appears an extract from a paper read by me before the 
Victoria Institute, on some microscopic contrivances ; and the 
new edition of Mr. Hogg’s excellent work, in which some of 
my processes are noticed; and beg now to supply two or 
three memoranda necessary to make them more intelligible. 
In the description of my steam-bath, the word “ earth” ap- 
pears instead of “ cork,” and is rendered by Mr. Hogg “ clay 
or luting.” The escape-pipe for the steam is simply fitted in 
a wide cork, which is more cleanly and convenient than 
luting would be. I seem to have omitted mention of the 
uses of this bath. It is designed to soften objects which have 
been long kept in a dry state, or which are naturally too hard 
to be readily mounted; also to prepare woods for cutting 
sections, and to flatten the sections themselves when they 
have curled in drying. The word “ eventually,” in the men- 
tion of cyanide of potassium as a killing agent, should be 
“eminently ;” but this is a trivial error, as the sense is eyi- 
dent. I have, since that paper was written, used the cyanide 
