. Manual of bacteriology. Bacteriology. 64 METHODS OF CULTIVATION OF nected from the hydrogen apparatus. In the case of flask (2), first the exit tube and then the entrance tube are sealed off in the flame before the flask is disconnected from the hydrogen ap- paratus. It is well in the case of both flasks to run some melted paraffin all over the rubber stopper. Sometimes much gas is evolved by anaerobes, and in dealing with an organism where this will occur, provision must be made for its escape. This is conveniently done by leading down the exit tube, and letting the end just dip
. Manual of bacteriology. Bacteriology. 64 METHODS OF CULTIVATION OF nected from the hydrogen apparatus. In the case of flask (2), first the exit tube and then the entrance tube are sealed off in the flame before the flask is disconnected from the hydrogen ap- paratus. It is well in the case of both flasks to run some melted paraffin all over the rubber stopper. Sometimes much gas is evolved by anaerobes, and in dealing with an organism where this will occur, provision must be made for its escape. This is conveniently done by leading down the exit tube, and letting the end just dip into a trough of mercury (Fig. 28), or into mer- „ cury in a httle bottle tied on to the end of the exit tube. The press- ure of gas within causes an escape at the mercury contact, which at the same time acts as an efficient valve. The method of culture in fluid media is used to obtain the soluble products of such anaerobes as the tetanus bacillus. Dr. W. H. Park of New York has recently introduced a very simple method for making anae- robic cultures in fluid media. An Erlenmeyer flask containing a suitable quantity of medium is boiled in a water bath for ten or fifteen minutes, to drive off all dissolved oxygen, then rapidly cooled down and inoculated. Hot melted parafifin is now poured into the flask until it reaches a depth of 2 or 3 mm., and upon solidifying it forms a perfect seal, excluding the air completely, yet not adhering to the glass so strongly as to prevent escape of gases should any be formed by the growing anaerobes. Wright's Method of Anaerobic Culture. — Utilising Buchner's pyrogallic acid medium for the removal of oxygen, Wright has contrived two very ingenious methods for anaerobic culture in ordinary test-tubes. In the first method, which is applicable to both solid and fluid media (Fig. 29), after inoculating,- the cotton plug, always made of absorbent cotton, is cut oflF flush with the extremity of the tube, and pushed inwards to a distance of i cm. I
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