CULTURE OF ANAEROBES 



59 



22. Esmarch's roll- 

 tube adapted for culture 

 containing anaerobes. 



the upper part of the bell jar are two apertures furnished with 



ground stoppers, and through each of the latter passes a glass tube 



on which is a stop-cock. One tube, bent slightly just after 



passing through the stopper, extends 



nearly to the bottom of the chamber; x L 



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 two to four grammes of dry 



pyrogallic acid placed in it towards one 



side. Culture plates made in the usual 



way 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, opening 

 the tap, and giving a few strokes 

 of the latter. 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, 



FIG. 23. Bulloch's apparatus for 

 anaerobic plate cultures. 



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

 through the glass tubes, washes out the potash and prevents 



