n a
cylindrical copper box (30 cm. high by 12 cm. diameter) provided with a
"pull-off" lid. Inside each box is a copper stirrup with a circular
bottom, upon which the plates rest, and by means of which each can be
raised in turn to the mouth of the box (Fig. 9) for removal.

~Capsules~ (Fig. 8, b and c).--These are Petri's dishes of smaller
diameter but greater depth than those termed plates. Two sizes will be
found especially useful--viz., 4 cm. diameter by 2 cm. high, capacity
about 14 c.c.; and 5 cm. diameter by 2 cm. high, capacity about 25 c.c.
These are stored in copper cylinders of similar construction to those
used for plates, but measuring 20 by 6 cm. and 20 by 7 cm.,
respectively.

[Illustration: FIG. 8.--Petri dish (a), and capsules (b, c).]

[Illustration: FIG. 9.--Plate box with stirrup.]

~Graduated Pipettes.~--Several varieties of these are required, viz.:

1. Pipettes of 1 c.c. capacity graduated in 0.1 c.c.

2. Pipettes of 1 c.c. capacity graduated in 0.01 c.c. (Fig. 10, a).

3. Pipettes of 10 c.c. capacity graduated in 0.1 c.c. (Fig. 10, b).

These should be about 30 cm. in length (1 and 2 of fairly narrow bore),
graduated to the extreme point, and having at least a 10 cm. length of
clear space between the first graduation and the upper end; the open
mouth should be plugged with cotton-wool. Each variety should be
sterilised and stored in a separate cylindrical copper case some 36 by 6
cm., with "pull-off" lid, upon which is stamped, in plain figures, the
capacity of the contained pipettes.

[Illustration: FIG. 10.--Measuring pipettes, a and b.]

The laboratory should also be provided with a complete set of "Standard"
graduated pipettes, each pipette in the set being stamped and
authenticated by a certificate from one of the recognised Physical
Measurement Laboratories, such as Charlottenburg. These instruments are
expensive and should be reserved solely for standardising the pipettes
in ordinary use, and for calibrating small pipettes manufactured in the
laboratory. Such a set should comprise, at least, pipettes delivering 10
c.c., 5 c.c., 2.5 c.c., 2 c.c., 1 c.c., 0.5 c.c., 0.25 c.c., 0.2 c.c.,
0.1 c.c., 0.05 c.c., and 0.01 c.c., respectively.

In the immediately following sections are described small pieces of
glass apparatus which should be prepared in the laboratory from glass
tubing of various sizes. In their preparation three articles are
essential; first a three-square hard-steel fi