NOTES AND QUERIES. ; 55 
ILLUMINATION OF SEMI-OPAQUE Osyects.—As the method of 
mounting insect preparations without pressure is becoming general, 
reference to the illumination of such objects on microscopical 
examination of them may be useful. It is obvious that objects 
so mounted must necessarily vary in their transparency, parts of 
them being more or less opaque; but much benefit, it has been 
observed, may be found from the use of the condensing lens above 
the object, at the same time throwing the light up from the 
reflecting mirror below. A specimen of the Czmex mounted in 
balsam by the carbolic process affords a good exemplification of 
such double illumination.—A. M. M. J. 
[Carbolic acid liquified by the addition of a few drops of water 
has long been used in this country for mounting insects without 
pressure. We were shown specimens of Czmex lectularius mounted 
in this manner at the Chester Soiree of 1880.—Eb. | 
EXcHANGE D1atoms.—Fossil diatoms from Bohemia and Han- 
over in exchange for micro-material, mounted or unmounted. T. 
C. Rinnboéck, 14, Simmering, near Vienna, Austria. 
MICROSCOPICAL SECTION.—At a joint meeting of the Manchester 
Literary and Philosophical Society and the Microscopical and 
Natural History Section of the Society, held on the 12th Decem- 
ber, Mr. John Boyd exhibited a fine living specimen of Argulus 
Joliaceus, a parasite of the carp. 
Mr. Charles Bailey, F.L.S., made some remarks on the occurrence 
of Selinum carvifolia in Lincolnshire, and of otamogeton ziztt in 
Lancashire and Westmoreland, and mentioned the localities where 
he had met with them respectively. 
Mr. R. D. Darbishire. B.A., F.G.S., gave an account of dredg- 
ings made by him in company with Dr. A. Milnes Marshall and 
Mr. Archer, at Oban, in Sept. last, and exhibited specimens of a 
considerable variety of animals taken. 
Professor A. M. Marshall gave a detailed description of three 
forms of Pennatulida met with during the dredging, and suggested 
the desirability of the section undertaking or taking part in similar 
excursions in future years. 
LANTERN TRANSPARENCIES.—A growing want has for some time 
been felt by lecturers on biological subjects, and especially by those 
whose lot it is to address large audiences or classes, of a good series 
of lantern slides, which would do for biology what has been so well 
done for physical science by York’s series of slides. The ever- 
increasing use of the oxyhydrogen lantern as a means of illustration, 
especially with popular audiences, renders this need more apparent. 
Arrangements have, however, now been made with Messrs. York 
