
. The Willows, Fallowfield, Manchester ; 
324 THE NORTHERN MICROSCOPIST. 

NOTICES TO CORRESPONDENTS. 
All communications should be 
addressed to Mr. George E. Davis, 
and matter intended for publication | 
must reach us not later than the 14th 
of the month. 
All communications must be accom- 
panied by the name and address of 
the writers, not necessarily for publica- 
tion, but as a guarantee of good faith. 
Cheques and money orders to be made 
payable to George E. Davis, the latter 
at the Manchester Chief Office. 

H. S., London.—We hope to be able 
to announce a change in the December | 
number, but our arrangements are not | 
yet made. ) 
H. S., Ipswich.—The objectives you | 
name are of foreign make. This would 
be patent to you if you took the front | 
cloak away. 
D. B.—No, Our mind is made up, | 
and no amount of encouragement will . 
induce us to debate the subject with | 
one who is evidently unacquainted with | 
the first principles of optics, | 
W. M.—You are mistaken, we have | 
no interest in the aperture shutter, and 
if you ‘‘can get as much penetration 
without it,” why do so by all means. 
D. D.—The fungus is Avegma bul- 
bosum ; it may be mounted in balsam 
and benzol. It would be impossible 
for us to start such a department as 
that you mention, at least at present. 
F. H,—We are surprised that you 
should object to the use of the aperture 
shutter ‘‘ on account of the aberrations 
it introduces,” and then state obtaining 
penetration by ‘‘ shortening the tube.” 
Do you not know that objectives as a 
tule are corrected for the full length of 
tube, and that you are disturbing the 
corrections at any other length. 
EXCHANGE COLUMN FOR 
SLIDES AND RAW MATERIAL. 
Communications not exceeding 24 words 
are inserted in thiscolumn free. They must 
reach us before the 14th of each month. 
Exchangers may adopt a nom-de-plume under 
care of the Editor, but in this case all replies 
must be accompanied with a penny stamp 
for each letter to cover postage, 
OcULARS.—Two good oculars two- 
inch (a pair) in exchange for well 
mounted slides.—H. A., care of the 
Editor. 
ScoTcH “ Disruption Worthies,” by 
Wylie, complete in 1§ two shilling 
clean and perfect parts. Wanted 
micro. slides, accessories, or offers. 
Morrison, 148, Clarence-street, Bolton. 
ACCESSORIES.—A few accessories in 
exchange for well mounted slides.— 
Pyro, care of Editor. 
LICHENS.— Wanted mounted speci- 
mens, or sections, in exchange for 
other lichens, or stained vegetable 
sections.—A. J. Doherty, 21, Barton- 
street, Moss Side, Manchester. 
SECTION CUTTER in exchange, has 
graduated top ring and two screws for 
holding objects in position.— Mrcro- 
TOME, care of the Editor. 
INJECTIONS. — Wanted well mounted 
micro, slides for unmounted opaque in- 
jections.—M. D., 2, WestburyGardens, 
Clapham Park, London, S. W. 
Raw MATERIAL.—Accumulation of 
micro.-material, especially fungi for 
mounted objects, clean diatioms, dryed 
plants or insects.—G. H. Bryan, 
Thornlea, Cambridge. 
DiaToMs WANTED.—Mounted or 
unmounted microscopic objects for 
good gatherings of Campylodiscus casta- 
lus, Meridian circulare, Achnanthes 
longipes, &c. Liberal exchange given. 
W. White, 7, Warden-place, York- 
street, Nottingham. 
AIR PumMp.—A small air pump, cost 
thirty shillings, in exchange for well 
mounted slides.—F.C.S., care of the 
Editor of this Journal. 
