fingers, must be at once reported to
the bacteriologist in charge.

II. GLASS APPARATUS IN COMMON USE.

The equipment of the bacteriological laboratory, so far as the glass
apparatus is concerned, differs but little from that of a chemical
laboratory, and the cleanliness of the apparatus is equally important.
The glassware comprised in the following list, in addition to being
clean, must be stored in a sterile or germ-free condition.

~Test-tubes.~--It is convenient to keep several sizes of test-tubes in
stock, to meet special requirements, viz.:

1. ~18 x 1.5~ cm., to contain media for ordinary tube cultivations.

2. ~18 x 1.3~ cm., to contain media used for pouring plate cultivations,
and also for holding sterile "swabs."

3. ~18 x 2~ cm., to contain wedges of potato, beetroot, or other vegetable
media.

4. ~13 x 1.5~ cm., to contain inspissated blood-serum.

The tubes should be made from the best German potash glass,
"blue-lined," stout and heavy, with the edge of the mouth of the tube
_slightly_ turned over, but not to such an extent as to form a definite
rim. (Cost about $1.50, or 6 shillings per gross.) Such tubes are
expensive it is true, but they are sufficiently stout to resist rough
handling, do not usually break if accidentally allowed to drop (a point
of some moment when dealing with cultures of pathogenic bacteria), can
be cleaned, sterilised, and used over and over again, and by their
length of life fully justify their initial expense.

A point be noted is that the manufacturers rarely turn out such tubes as
these absolutely uniform in calibre, and a batch of 18 by 1.5 cm. tubes
usually contains such extreme sizes as 18 by 2 cm. and 18 by 1.3 cm.
Consequently, if a set of standard tubes is kept for comparison or
callipers are used each new supply of so-called 18 by 1.5 cm. tubes may
be easily sorted out into these three sizes, and so simplify ordering.

5. ~5 x 0.7~ cm., for use in the inverted position inside the tubes
containing carbohydrate media, as gas-collecting tubes.

These tubes, "unrimmed," may be of common thin glass as less than two
per cent. are fit for use a second time.

[Illustration: FIG. 1.--Bohemian flask.]

[Illustration: FIG. 2.--Pear-shaped flask.]

[Illustration: FIG. 3.--Erlenmeyer flask (narrow neck).]

~Bohemian Flasks~ (Fig. 1).--These are the ordinary flasks of the chemical
laboratory. A good variety, ranging in capacity from 250 to 3000 c.c.,
sho