tion for the reception of
infected cover-glasses and infected pipettes, etc.

4. A square glazed earthenware box with a loose lining containing 2 per
cent. lysol solution for the reception of infected material and used
slides. The bottom of the lining is perforated so that when full the
lining and its contents can be lifted bodily out of the box, when the
disinfectant solution drains away and the slides, etc., can easily be
emptied out. The empty lining is then returned to the box with its
disinfectant solution (Fig. 61).

5. Bunsen burner provided with "peep-flame" by-pass.

6. Porcelain trough holding five or six hanging-drop slides (Fig. 62).

[Illustration: FIG. 62.--Hanging-drop slides: a, Double cell seen from
above; b, single cell seen from the side.]

The best form of hanging-drop slide is a modification of Boettcher's
glass ring slide, and is prepared by cementing a circular cell of tin,
13 to 15 mm. diameter, and 1 to 2 mm. in height, to the centre of a 3 by
1 slip by means of Canada balsam. It is often extremely convenient to
have two of these cells cemented close together on one slide (Fig. 62,
a).

Another form of hanging-drop slide is made in which a
circular or oval concavity or "cell" is ground out of the
centre of a 3 by 1 slip. These are more expensive, less
convenient to work with, and are more easily contaminated by
drops of material under examination, and should be carefully
avoided.

7. Three aluminium rods (Fig. 63), each about 25 cm. long and carrying a
piece of 0.015 gauge platino-iridium wire 7.5 cm. in length. The end of
one of the wires is bent round to form an oval loop, of about 1 mm. in
its short diameter, and is termed a loop or an oese; the terminal 3 or 4
mm. of another wire is flattened out by hammering it on a smooth iron
surface to form a "spatula"; the third is left untouched or is pointed
by the aid of a file. These instruments are used for inoculating culture
tubes and preparing specimens for microscopical examination.

[Illustration: FIG. 63.--Ends of platinum rods. a, loop; b, spatula;
c, needle.]

The method of mounting these wires may be described as follows:

Take a piece of aluminium wire 25 cm. long and about 0.25 cm. in
diameter, and drill a fine hole completely through the wire about a
centimetre from one end. Sink a straight narrow channel along one side
of the wire, in its long axis, from the hole to the nearest end, shallow
at