TUBERCULOSIS.

219

Kitasato's method of washing the sputum has been
modified and simplified by Czaplewski and Hensel.1 In
their studies of whooping-cough, instead of washing the
flakes in water in dishes, they shook them in peptone
water in test-tubes. The shaking in the test-tube being
so much more thorough than the washing in dishes, fewer
•'changes are necessary, three or four washings being
sufficient.

In 1887, Nocard and Roux gave a great impetus to
investigations upon tuberculosis by their discovery that
the addition of 4-8 per cent,
of glycerin to bouillon and
agar-agar made them suitable
for the development of the
bacillus, and that a much
more luxuriant development
could be obtained upon these
media than upon blood-se-
rum. The growth upon such
'' glycerin agar-agar'' (Fig.
62) very much resembles
that upon blood-serum. The
growth upon bouillon with
4 per cent, of glycerin is
also luxuriant. As tubercle
bacilli require considerable
oxygen for their proper devel-
opment, they grow only upon
the surface of the bouillon,
where a rather thick myco-
derma forms. The surface-
growth is rather brittle, and after a time gradually sub-
sides fragment by fragment.

The tubercle bacillus can be grown in gelatin to which
glycerin has been added, but as its development takes
place only at 37°-38° C., a temperature at which gelatin is
always liquid, its use for the purpose is disadvantageous.

1 Centralbl.f. Bakt. z/. Parasitenk., xxii., Nos. 22 and 23, p. 643.

FIG. 62.—Bacillus tuberculosis on
"glycerin agar-agar."