44 AIDS TO BACTERIOLOGY 



Buchner's Tube. A large test-tube, having a constric- 

 tion a little above the bottom, and fitted with a rubber 

 stopper, well vaselined. The inoculated tube is placed in 

 the Buchner's tube, and rests on the constricted portion. 

 Some strong aqueous solution of pyrogallic acid is then 

 run into the outside tube, followed by an equal volume of 

 20 per cent, caustic potash solution. Without allowing 

 the pyrogallic acid and potash to mix, the rubber stopper 

 is quickly inserted, and the solutions in the tube below 

 the constriction mixed. Stoppered glass bottles may be 

 used for the purpose. 



In FrdnkeTs method a large, strong test-tube contain- 

 ing the medium is fitted with a rubber cork, through 

 which pass two glass tubes, bent at right angles just above 

 the stopper, and the ends drawn out. One tube should 

 reach almost to the bottom of the tube, and the other just 

 through the cork. After sterilisation and inoculation, 

 hydrogen is passed through the longer tube and escapes 

 by the shorter one. When all the air has been expelled 

 the tubes are sealed in a Bunsen flame, the shorter tube 

 being done first. 



Bullock's apparatus consists of a large bell- jar with 

 ground flange, which can be luted to a plate of ground- 

 glass with a suitable grease or resin ointment. Through 

 the top, two tubules with ground stoppers, and provided 

 with stopcocks, pass. By means of these hydrogen can be 

 passed through the bell- jar to displace the air, when the stop- 

 cocks are closed. A dish of alkaline pyrogallol may be placed 

 at the bottom to absorb oxygen in case of a slight leak. 



Discrete colonies of organisms may be obtained by 

 smearing the infected loop over the surfaces of three or four 

 slanted media tubes in turn, without reinfecting. The 

 tubes are incubated in a wide-mouthed stoppered bottle 

 with ample volumes of pyrogallic acid and soda~solutions. 

 One gramme of the former should be allowed for every 

 100 c.c. of air space. 



Animal Inoculations. Animal inoculations may be 

 required, among other reasons, (a) to enhance the viru- 

 lence of an organism which has become attenuated through 

 culture on media the infective agent may be injected 

 alone, with another pathogenic organism, or with a toxin 

 to lower the animal's resistance; (b) to identify an organ- 

 ism; (c) to obtain a pure culture. 



