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DIPHTHERIA.                           287

accurate examinations can be made. The method re-
quires some apparatus, though a competent bacteriologist
can often make shift with a bake-oven, a wash-boiler,
and other household furniture instead of the regular
sterilizers and incubators, which are expensive.

When it is desired to make a bacteriologic diagnosis
of a suspected case of diphtheria or to secure the bacillus
in pure culture, a sterile platinum wire having a small
loop at the end, or a swab made by wrapping a little
cotton around the end of a piece of wire and carefully
sterilizing in a test-tube, is introduced into the throat
and touched to the false membrane, after which it is
smeared carefully ovei the surface of at least three of
the blood-serum-mixture tubes, without either again
touching the throat or being sterilized. The tubes thus
inoculated are stood away in an incubating oven at the
temperature of 37 C. for twelve hours, then examined.
If the diphtheria bacillus is present upon the first and
second tubes, there will be a smeary yellowish-white layer,
with outlying colonies on the second tube, while the third
tube will show rather large isolated whitish or slightly
yellowish colonies, smooth in appearance, but rather ir-
regular in outline. Very often the colonies are china-
white in appearance. These colonies, if found by micro-
scopic examination to be made up of diphtheria bacilli,
will confirm the diagnosis of diphtheria, and will at the
same time give pure cultures when transplanted. There
are very few other bacilli which grow so rapidly upon
Loffler's mixture, and scarcely one other which is found
in the throat.

Ohlmacher recommends the microscopic examination
of the still invisible growth in five hours. A platinum
loop is rubbed over the inoculated surface ; the material
secured is then mixed with distilled water, dried on a
cover-glass, stained with methylene blue, and examined.
This method, if reliable, will be very valuable in making
an early diagnosis preparatory to the use of the antitoxin.

The presence of diphtheria bacilli in material taken