ically at 20 deg. C.

(C) Sloped glucose formate agar to incubate anaerobically at 37 deg. C.

Glucose formate bouillon to incubate anaerobically at 37 deg. C.

(D) Sloped glucose formate gelatine to incubate anaerobically at
20 deg. C.

Glucose formate bouillon to incubate anaerobically at 20 deg. C.

2. Seal the cultures forming set B in Buchner's tubes (_vide_ page 239).

3. Seal the cultures forming set C in Bulloch's apparatus; exhaust the
air by means of a vacuum pump, and provide for the absorption of any
residual oxygen by the introduction of pyrogallic acid and caustic soda
in solution (_vide_ page 245). Treat set D in the same way.

4. Observe the cultivations macroscopically and microscopically at
intervals of twenty-four hours until the completion, if necessary, of
seven days' incubation.

5. Control these results.

_Gases Other than Oxygen._--

_Apparatus Required:_

Bulloch's apparatus.
Sterile gas filter (_vide_ page 40).
Gasometer containing the gas it is desired to test (SO_{2}, N_{2}O, NO,
CO_{2}, etc.) or gas generator for its production.

METHOD.--

1. Prepare at least seven tube cultivations upon solid media and deposit
them in Bulloch's apparatus.

2. Connect up the inlet tube of the Bulloch's jar with the sterile gas
filter, and this again with the delivery tube of the gasometer or gas
generator.

3. Open both stop-cocks of the Bulloch's apparatus and pass the gas
through until it has completely replaced the air in the bell jar as
shown by the result of analyses of samples collected from the exit tube.

4. Incubate under optimum conditions as to temperature.

5. Examine the cultivations at intervals of twenty-four hours, until the
completion of seven days.

6. Remove one tube from the interior of the apparatus each day. If no
growth is visible, incubate the tube under optimum conditions as to
temperature _and_ atmosphere, and in this way determine the length of
exposure to the action of the gas necessary to kill the organisms under
observation.

7. Control these results.

~II. Temperature.~--

(A) _Range._--

1. Prepare a series of ten tube cultivations, in fluid media, of optimum
reaction.

2. Arrange a series of incubators at fixed temperatures, varying 5 deg. C.
and including temperatures between 5 deg. C. and 50 deg. C.

(In the absence of a sufficient number of incubators utilise the
water-bath employed in testing the thermal death-point of