APPAKATUS FOR ANAEROBIC CULTURE 



63 



the chamber ; the other terminates immediately below the 

 stopper. In using the apparatus there is set on the base-plate 

 a shallow dish, of slightly less diameter than that of the bell-jar, 

 and having a little heap of from 2 to 4 grms. of dry pyrogallic 

 acid placed in it towards one side. Culture plates, which should 

 be of rather greater thickness than for ordinary aerobic work, 

 can be stacked on a frame of glass rods resting on the edges of 

 the dish, or a beaker containing culture tubes can be placed in 

 it. The bell-jar is then placed in position so that the longer 

 glass tube is situated over that part of the bottom of the 

 shallow dish farthest away from the pyrogallic acid, and the 

 bottom and stoppers are luted. 

 The air in the bell-jar is now 

 expelled by passing a current of 

 hydrogen through the short glass 

 tube, and both stoppers are closed. 

 A partial vacuum is then effected 

 in the jar by connecting up the 

 short tube with an air-pump, open- 

 ing the tap, and giving a few 

 strokes of the pump. A solution 

 of 109 grms. solid caustic potash 

 dissolved in 145 c.c. water is made, 

 and into the vessel containing it 

 a rubber tube connected with the 

 long glass tube is made to dip, 

 and the stopper of the latter being 

 opened, the fluid is forced into the 

 chamber and spreads over the 

 bottom of the shallow dish; 



potassium pyrogallate is thus formed, which absorbs any free 

 oxygen still present. Before the whole of the fluid is forced 

 in, the rubber tube is placed in a little boiled water, and this, 

 passing through the glass tubes, washes out the potash and 

 prevents erosion of the glass. The whole apparatus may be 

 placed in the incubator till growth occurs. 



M'lntosh and Tildes Anaerobic Jar. — These authors have designed 

 a jar in which tubes may be incubated under anaerobic conditions, the 

 oxygen being absorbed by spongy palladiumi A glass pickle jar, fitted 

 with a metal lid screwing down on a rubber washer, is employed. Into 

 a hole in this lid there is soldered a small stopcock such as is used in 

 moiiel steam-engines. A bracket of sheet brass, carrying a capsule of fine 

 brass or copper gauze, is fixed to the inner end of the stopcock by means 

 of the screw-on collar of the latter (Fig. 19). 0'25 gr. fine asbestos wool 

 is placed in a porcelain capsule and soaked in T5 c.c. 10 per cent. 



Fig. 18. — Bulloch's apparatus for 

 anaerobic plate cultures. 



