Page 782 - My FlipBook

792 DENTAL CABIES. : ;
1. A large double-walled incubator, with gas-regulator for maintain-
ing any desired constant temperature.
Fig. 407. 2. A Koch sterilizer.
3. A damp chamber. (See Fig. 407.)
4. A drying-oven for sterilizing instru-
ments, glass vessels, etc., at a temperature
of 150° C.
5. A good microscope with either water or
oil immersion.
It is not necessary to mention the smaller
instruments, glass vessels, etc., etc., nor the
ai)paratus necessary for making a chemical
analysis of the products of the fermentation
Damp Chamber : n, shallow glass these are sufficiently familiar to every one.
vessel partially filled with water;
h, glass globe lined with wet bib- To avoid repetition, I will say here that
ulous paper ; c, metallic >taiid lor all vessels and instruments used in the cul-
culture-tubes.
ture experiments were purified in the flame
of a J^unsen burner when practicable, otherwise by exposing for fifteen
minutes in the drying-oven to a temperature of 150° to 160° C. (302°
to 320° F.), and that all substances used as culture substrata M^ere ster-
ilized four times by exposure, at intervals of twelve hours, for half an
hour, to steam at 100° C, in a Koch sterilizer. Furthermore, all infec-
tions from carious dentine were made as follows : The cavity of a
freshlv-extracted carious tooth is cleared of food and carefully brushed
over with a pledget of cotton dij^ped in carbolic acid (90 per cent.).
The acid is then thoroughly absorbed by means of bibulous paper, and
layer after layer of the soft dentine removed with a repeatedly purified
instrument until the deeper jiarts are reached ; then a portion of the
clean soft dentine scarcely as large as a pin-head is removed and quickly
brought into or upon the culture medium.
Infections from the mouth were made by scratching upon the surface
of the mucous membrane of the cheek or the margin of the gum with
the end of a clean platinum wire, and then dipping it into the culture
medium. The materials used for culture were
Ao. /. Sterilized saliva 50.0
Sugar ' 1.0
Starch 0.5

No. 2. Sterilized milk.
No. 3. Decoction of malt 50.0
Sugar .... 1.0

The malt decoction is made by boiling, with slight evaporation, 20.0*
dry malt with 120.0 water for ten minutes, and filtering.
No. J/,. Sterilized saliva 50.0
Water 50.0
Starch 20.0
Sugar 2.0