198 THE MICROSCOPICAL NEWS. 
with reflected light. Some species exhibit their structure beautifully 
when viewed as apaque objects when mounted thus. 
The most ready, and the most common way to mount these 
objects is to place them dry in cells as apaque objects. For the 
purpose of study, or to make a systematic collection, it is best to 
mount several of one species only upon a slide, arranging them so 
as to show different stages of growth, difference of form, etc. To 
fasten them to the bottom of the cell, I first make a little dab of 
cement, using either stratena or liquid marine glue, upon the spot 
I design to place the shell with the point of a sharpened match. 
Care should be taken not to get on teo much cement or it will 
penetrate the shell or form an unsightly mass surrounding.it. Then 
I take up the shell with the forceps, or with the needle wetted by 
turpentine, as before described, and put it in place. 
Not being satisfied with the ordinary slides and cells for this 
class of objects, I have devised a slide which serves the purpose 
admirably,—it is made as follows: The slide itself is of wood of the 
ordinary size and about 54, inch thick. Through its centre is bored a 
hole % inch in diameter, over the back of this is pasted a strip of 
stout paper. The hole in the slide with the paper back constitutes 
the cell. In the bottom of the cell is pasted a disk of coloured 
paper, cut with a gun-wad punch, to serve as a back ground for 
the “mount.” To give a neat finish a brass curtain-ring which just 
fits in the hole is fastened in with a bit of cement. The edges of 
the slide are now bound or covered, with a bit of coloured tissue 
paper. ‘The shell may now be arranged in the cell, and the cover 
glass dropped in upon the brass ring, the top of which has been 
covered with cement. A suitable label, the whole size of the slide, 
is now pasted on the front, and a plain one may be put on the back. 
Should a shell be very rare and it is desirable to show both sides, 
a piece of thin glass may be let into the back of the slide, and the 
curtain-ring placed upon this instead of the paper back-ground. 
Such a slide would need a hole in the back as well as in the front 
label. 
When these slides are finished with pretty and suitable labels 
they make a fine appearance, pack and carry as easily as so many 
slips of wood, and if made of white bass wood do not warp. The 
porosity of the wood prevents any accumulation of moisture upon 
the cover glass, and upon the whole, these slides are very satis- 
factory. . 
I wish to call attention to the desirability of using some other 
colour for the back ground of apaque “mounts” than black. After 
much experimenting with various colours, I have settled upon that 
afforded by a pigment called “crimson lake.” I use either this or 
a piece of glazed paper of the same colour. When the object is 
white, or nearly so, I use this colour exclusively, but when it has 
