THE CULTURE OF ANAEROBIC BACTERIA. 313 



be used for the gas or for the pyrogallate method. The 

 apparatus shown in Fig 53 is provided with a slightly dif- 

 ferent stopper, and can be used for the gas, pyrogallate or^ 

 vacuum method. In the latter case the wider end of the 

 stopper should be provided with a piece of rubber tubing, 

 which should be clamped tight. The apparatus provided 

 with the ordinary stopper (Figs. 51-52), should never be 

 used for vacuum work since the atmospheric pressure will 

 cause the stopper to wedge so firmly that it will be almost 

 impossible to turn. 



The lower half of the apparatus should have an internal diameter 

 of 12 cm. and an inside height of 12 cm. The apparatus can hold 6 or 

 S Petri dishes. It can be used for small flasks, or for a large number 

 of tube cultures. The total height of the apparatus should not ex- 

 ceed 24 cm. Each flange should be 2 cm. wide and f cm. thick. The 

 outer circumference should be ground vertically so that a rubber band 

 can be employed to effectually seal the apparatus. It is necessary, 

 therefore, that the diameter of the top and bottom should be exactly 

 the same. The unground surfaces of the flanges should be parallel or 

 nearly so in order that the clamps will not slip off. 



The gelatin or agar Petri dishes are placed in the lower 

 jar. It is unnecessary and undesirable to remove the tops. 

 The upper part is then placed in position and the wide rub- 

 ber band is slipped over the circumference. Three clamps 

 are then applied to the flanges. A slit piece of rubber tub- 

 ing should be slipped over the jaws of the clamps. 1 Hydro- 

 gen is then passed through the apparatus in the manner 

 described on p. 312. Finally the stopper is turned and the 

 apparatus set aside for the organisms to develop. 



The pyrogallate method can be used with excellent re- 

 sults. 3-5 g. of pyrogallic acid are placed in a glass dish, 

 which is about 10 cm. in diameter and about 3 cm. high. 

 This is placed on the bottom of the lower jar and covered 

 with a strip of glass about 5 cm. wide. The Petri dishes 

 are then stacked on top. The upper half of the apparatus 



1 No. 1. Amateur vise made by the Phoenix Hardware Mnf g. Co., 

 Phoenix, N. Y. 



