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NOTICES TO CORRESPONDENTS. 
All communications should be ad- 
dressed to the Editor, Mr. George E. 
Davis, Dagmar Villa, Heaton Chapel, 
Stockport ; 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. 
K. F. A.—We use nothing but cells 
built up of old gold-size, fastening on 
the cover with Brown Varnish, finally 
going over the whole with new gold- 
size. The Brown Varnish may be ob- 
tained from Mr. Ward, whose adver- 
tisement is upon the cover. 
H. C. C.—yYou will see we have 
drawn attention to the subject of your 
note in our ‘‘ Notes and Queries” 
column. 
W. E. A. A.—Paper received ; shall 
be glad to hear from you occasionally 
on the subject of microscopy. 
_ A. A.—Get ‘Ponds and Ditches,” 
which may be had of any bookseller. 
P. C. R.—The Journal of the Royal 
Microscopical Society will give you all 
the information you require on ‘‘ An- 
gular Apertures.” We are afraid the 
subject would be too deep and unin- 
teresting for the majority of our readers. 
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, 
Well-mounted slides of Palate of 
Cyclastoma elegans, in exchange for 
THE NORTHERN MICROSCOPIST. 
other good microscopical objects, 
mounted. M. Farhall, 3, St. John’s- 
road, Dover. 
INJECTED specimens of kidney, 
tongue, and liver, also very fine slides 
of human teeth, prepared according to 
the method of Dr. Bodecker, showing 
the protoplasmic net-work between 
the dentinal canaliculi, in exchange 
for first-class histological and patholo- 
gical slides or other good specimens. 
L. Williams, North Vassalboro, 
Me., U.S.A. 
SALE AND EXCHANGE COLUMN 
FOR APPARATUS, BOOKS, Eto. 
Advertisements in this column are inserted 
at the rate 4d. for each 12 words or portions 
of twelve. 
Advertisers may adopt a nom-de-plume 
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replies must be accompanied by a penny 
stamp for each letter, to cover postage. 
All Advertisements intended for insertion 
in this column must reach us before the 14th 
of each month, 
PHOTO-MICROGRAPHS of scientific 
value may be obtained from Mr. J. H. 
Jennings. 14 Beech Avenue, Notting- 
ham. They illustrate structure of 
typical rocks and minerals, sedimentary 
rocks with forams, and subjects in en- 
tomology. Price 5s. per dozen, or in 
exchange for really good petrological 
or entomological slides. 
VALLISNERIA SPIRALIS, assorted 
weeds and trumpet snails for aqua- 
rium, 8d. per dozen free. Mr. Keall, 
Chemist, Swansea. 
IMMERSION OBJECTIVE.—A splen- 
did one-fifteenth immersion objective, 
as good as new. Price £7. B., care 
of the Editor of THE NORTHERN 
MICROSCOPIST. 
NITELLA TRANSLUCENS.—Willsend 
some of this weed on receipt of mount 
or material. E. B. L. BRALEY, 2, 
Burlington Buildings, Redland Park, 
Bristol. 
