PROCEEDINGS OF SOCIETIES, 215 
I cannot perceive the slightest alteration in it: the ring experi- 
mented upon is on the table. The cells which I now exhibit 
were cut with a lathe and an ordinary chisel, of a thickness of a 
little more than the microscopic thin glass and upwards, and 
cemented by heat with marine glue to the glass slide. It 
will be perceived that the thinnest has not altered its shape in 
the slightest degree. 
Mr. Bailey, of No. 162, Fenchurch Street, City, has undertaken 
to supply these rings from 6d. to 8d. per dozen, according to size 
and thickness. 
In examining a slide of Polycystina a few days ago with oblique 
light thrown by the mirror, my attention was attracted by seeing 
the black ground more intense and the object better brought out 
while my hand was employed in moving the reflector ; I found this 
to proceed from the shadow—the hand cast across the plane of 
the object-glass. This suggested placing a piece of dead black 
_ paper on the table beneath the objective, or still better, at the 
bottom of a pill-box mounted on the stem carrying the mirror, 
which gave an increased improvement in the back ground. I 
subsequently substituted for the sombre colour papers stained 
with green, blue, yellow, red, pink, orange, &c., with a pleasing 
and I think instructive effect—very grateful to the eye, especially 
so in respect to the greens and the blues. I propose to try if the 
spot lens can be used with a like result; in the mean time, if not 
already observed and recorded, it may be interesting to your 
readers. 
Lun’s Carp-Bosarpd CELLs for MOUNTING DRY OBJECTS. 
Mr. Henry Lex introduces to the Society specimens of cells 
cut from tudes of card-board, which being cheap to purchase, 
ls. per gross, and easily made, will be found very useful in the 
mounting of dry and opaque objects. As these are now much in 
favour for the binocular microscope, it is hoped that cheap cells 
adapted to them will prove acceptable to both amateur and pro- 
fessional mounters. ‘They are made in the same manner as the 
sides of pill-boxes, by rollmg gummed paper on a wooden mandril, 
and cutting rings from the tube thus formed when dry and 
hard. It will be seen that they can readily be made of any re- 
quired depth, diameter, or thickness. : 
“On the use of black and coloured paper as a background for 
objects,” by Mr. Hall. 
‘*On anew Achromatic Condenser,” by Mr. J. Webster. 
“ On the structure and formation of the Sarcolemma of Striped 
Muscle, and of the exact relation of the nerves, vessels, and air- 
tubes in the case of Insects to the contractile Tissue of Muscle,” 
by Dr. Lionel S. Beale. 
