CULTUKE OF ANAEROBES 



59 



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; 



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 _ 

 f , . P., FIG. 22. Esmarchs roll- 



tube is situated over that part of the tabe adapted for cu]ture 



bottom of the shallow dish farthest away containing anaerobes. 



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 



FIG. 23.-Bulloch's apparatus for formed > which absorbs an ? free 



anaerobic plate cultures. 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 



