STORING "TUBED" MEDIA 



161 



ated in cubic centimetres up to 20, by pouring into it 

 measured quantities of water and marking the various 

 levels on the outside with a writing diamond. 



Fluid media containing carbohydrates are filled into 

 fermentation tubes (vide Fig. 21); or into ordinary 

 media tubes which already have smaller tubes, inverted, 

 inside them (Fig. 104) , to collect the products of growth 

 of gas-forming bacteria. When first filled, the small 

 tubes float on the surface of the medium after the first 



FIG. 103. Separatory funnel and three-way tap arranged for tubing media. 

 FIG. 104. Gas tube (Durham). 



sterilisation nearly all the air is replaced by the medium, 

 and after the final sterilisation the gas tubes will be 

 submerged and completely filled with the medium. 

 Storing "Tubed" Media. Media after being tubed 

 are best stored by packing, in the vertical position, 

 in oblong boxes having an internal measurement of 

 37 cm. long by 12 cm. wide by 10 cm. deep. Each 

 box (Fig. 105) has a movable partition formed by the 



