TUBERCULOSIS. 215

clean conical glasses and measured therein. The- pro-
portion of muco-purulent to fluid matter was noted.
Depending upon the degree of viscidity and number of
bacilli present in the sputum, a varying amount of 5 per
cent, caustic potash solution was added to it (from one-
sixth to an equal volume), and after the caustic potash
had rendered the sputum perfectly fluid more or less water
was added to dilute the mixture. The sputum, having
been measured, was poured into a perfectly clean wide-
mouthed bottle containing fine sterilized gravel or broken
glass. Rinsings of a measured amount of the caustic pot-
ash solution were used to free the conical glass from what
matter might remain and were added to the sputum.
The contents of the bottle were agitated in a shaking
machine for five minutes, and allowed to stand until the
caustic potash solution had had time to act. As soon as
the sputum had become homogeneous an equal volume
of water was added, and the whole shaken again. The
sputum thus treated was of a pale-green or yellowish-
brown color, and contained only small fragments of elas-
tic tissue. It was allowed to stand two to four hours,
and then shaken again for five to ten minutes.

By means of a burette of original design drops of ex-
actly equal size were secured and caught upon clean
sterile cover-glasses. The drops were subsequently
spread into an even film by a very fine platinum wire,
while the cover-glass was rotated upon a "turn-table."
After spreading, the cover-glasses were laid upon a level
brass plate slightly warmed to facilitate drying. After
drying, the cover-glasses were coated with a serum film
by spraying, and the temperature raised to 8o°-~9O° C. to
coagulate the serum and retain the bacteria in place,
after which they were carefully stained with carbol-
fuchsin and decolorized with a solution of 150 parts of
water, 50 parts of alcohol, and 20-30 drops of pure sul-
phuric acid. Prior to this the cover-glass was washed in
three alcohols and subsequently in water, and if necessary
in acid and alcohol again.