156

PATHOGENIC BACTERIA.

hydrogen. In using Botkin's apparatus the uncovered
Petri dishes are placed one above the other in the rack c,
and covered with the bell-glass A. Liquid paraffin is
poured in the dish B until it is about half full. From a

Kipp's apparatus hydrogen
gas enters the little rubber
tube #, subsequently escap-
ing by the tube b. When
only pure hydrogen escapes
the rubber tubes a and b are
withdrawn, and the appa-
ratus remains filled with hy-
drogen. Lest a little oxygen
should remain, it is best to
have the dishes at the top
and bottom of the rack filled
with alkaline pyrogallic
acid. Tetanus can be cul-
tivated in this apparatus.

The jars recently intro-
duced by Novy are similar

FIG. 38.—Botkin's apparatus for mak-
ing anaerobic cultures.

in principle, depending
upon the replacement of the air by hydrogen. They are

FIG. 39.—Novy's jars for anaerobic cultures.

so constructed that when the stopper occupies a certain
relative position to the neck the gas can enter and exit,