252 
NOTES AND MEMORANDA. 
[Monthly Microscopical 
Journal, April 1, 1S69. 
to depend on laboratory testings in the purchase of his " orchella 
weed," or in determining its commercial value ; for it not unfrequently 
happens that a most promising Boccella even proves worthless, and is, 
as such, cast aside. 5. Colour-reaction, though interesting in itself 
in connection with the general subject of liclien colorific or colouring 
matters, affords no aid that can he depended on, either (a) to the syste- 
matist in defining species, or (h) to the dye-manufacturer in. determining 
the value of his " orchella weed." * ^ 
NOTES AND MEMOKANDA. 
Erratum in ¥o. II. of this Journal.— Through a slip of the pen, 
to which even the most precise writer is liable, the translator of the 
paper by M. Lacaze-Duthiers in the February number of the Journal, 
wrote of the supra as the sub-oesophagal ganglion. We ought to 
apologize to the intelligence of our readers for pointing out a mistake 
of this kind, as the ganglion in question is throughout spoken of as 
the dorsal or superior one, thus leaving no doubt as to the meaning 
of the context. But as we desire to be exact, and as we have a Avhole- 
some remembrance of the fantastic tricks of the " printer's devils " in 
the old journal, we call attention to what was certainly an error. We 
may mention also that we will esteem it a favour if our correspondents 
will point out the errata they may observe in our pages. We strive 
after accuracy, but we are by no means infallible. 
A^ew Eorm of Condenser, which is we believe — we have not 
yet had the pleasure of seeing it — a modification%of that known as 
Mr. Eeade's Kettle-drum, has been devised by Messrs. Powell and 
Lealand. We are informed that it is especially valuable in the 
examination of Diatomace^e. 
Mr. Eoss' Compressorinm. — Mr. Eoss has made some improve- 
ments in his compressorinm, which render it a suitable apparatus for 
research on specimens, such as infusoria and rotifers. The double 
inclined plane principle, worked by a finely graduated screw, which 
brings the two surfaces of the glasses together with any degree of 
slowness and compression, seems to work well. We had hoped to 
have placed a figure of this accessory before our readers, but owing 
to the engraver not having had the block cut in time we must defer 
a further account to our next number. 
The Provincial Microscopical Societies. — We are now in com- 
munication with most of the local Associations, and we hope ere long 
to cement relations with all. In the meantime, we shall feel obliged 
for any notices or notes that our correspondents can find time to send 
us. We desire to represent fairly and fully the labours of all British 
Microscopists. 
Dr. Bastian's Cement. — In reply to our correspondent, G. F., we 
may state that this cement, which will be found very useful by those 
