H. Goadby on making wet Preparations of Animal Substances. 19 
tions; for all such, a ced/, or a glass box, must now be prepared, 
and the following is the way to proceed. 
First, accurately measure the length, breadth, and substance 
of the preparation to be mounted; select a piece of flat glass of 
substance agreeing as nearly as possible with the thickness of the 
preparation and with a glazier’s diamond cut off two pieces from 
one-eighth to three-sixteenths of an inch wide, and of equal 
length; these are to form the sides of the cell; the ends must be 
of the same width but not so long. Although the cell should 
fit the preparation in regard to depth or thickness, a good space 
should always be allowed around the sides and ends, for example: 
I desire to make a cell for a preparation measuring one inch long, 
and five-eighths wide, I should make the cell one and a half inch 
long, and one inch wide, inside measure, when finished the prep- 
aration looks better, is more accessible to the microscope because 
the sides of the vessel are not in the way, and, what is most im- 
portant there is more room for preserving fluid than if the vessel 
be contracted to the actual size, or thereabouts of its contents. 
The depth should be exact for two reasons: one, that thereby 
the object is retained in the center of the cell, being lightly 
essed upon by the top, and bottom glasses; the other, that 
there being no greater substance of fluid between the object and 
the microscope than must needs be, a better definition of the ob- 
ject is obtained. ; 
When glass is cut with a diamond it always leaves a rugged, 
uneven surface; for example, when broken off, one piece of 
glass will present a series of projections, which have left corres- 
ponding cavities in the piece to which it was attached; when 
Placed together, they lock into each other and the addition of a 
thin layer of cement will form a perfect joint. 
Tavail myself of this fact in 
constructing cells of the kind fra 
just described, thus: fig. 1 rep- 
Tesents a piece of glass of the 
exact length and breadth, owé- 5 
side measure, that the cell is re- 
quired to be. i t 
The two long pieces, or sides : 
are first cut, and before breaking them off they are marked with 
the scratch diamond so as to include the ends. As the width of 
the cell is not always sufficient to admit a number of lines, I 
first make a diagonal mark, then 1 and 2—rarely 3, which is un- 
necessary. I now separate the pieces, discard number 5, ai 
take care to cement them to the bottom glass or slide, in the 
order in which they are marked, and to ensure accuracy in this 
spect, keep the marked surface upward. As it is necessar} ded 
have a bottom glass before we can cement the pieces just sci 
to give some 
