ANAEROBIC METHODS 227 



Cultivation without Oxygen. As we have already learned, 

 there is a group of bacteria to which the designation "anae- 

 robic" has been given, which are characterized by inability 

 to grow in the presence of free oxygen. For the cultivation 

 of the members of this group, a number of devices are 

 employed for the exclusion of free oxygen from the cultures. 



Method of Buchner. The plan suggested by Buchner, of 

 allowing the cultures to develop in an atmosphere robbed of 

 its oxygen by pyrogallic acid, gives very good results. In 

 this method the culture, which is either a slant- or stab- 

 culture in a test-tube, is placed tube, cotton plug, and all 

 into a larger tube, in the bottom of which have been deposited 

 1 gram of pyrogallic acid and 10 c.c. of yV normal caustic- 

 potash solution. The larger tube is then tightly plugged 

 with a rubber stopper. The oxygen is quickly absorbed 

 by the pyrogallic acid, and the organisms develop in the 

 remaining constituents of the atmosphere, viz., nitrogen, a 

 small amount of CO 2 , and a trace of ammonia. 



Method of C. Frdnkel. Carl Frankel suggested the fol- 

 lowing : the tube is first inoculated as if it were to be poured 

 as a plate or rolled as an ordinary Esmarch tube. The cotton 

 plug is then replaced by a rubber stopper, through which 

 pass two glass tubes. These must all have been sterilized 

 in the steam sterilizer before using. On the outer side of 

 the stopper these two tubes are bent at right angles to the 

 long axis of the test-tube into which they are to be placed, 

 and both are slightly drawn out in a gas-flame. Both of 

 these tubes must be provided, before sterilization, with 

 a plug of cotton; this is to prevent the access of foreign 

 organisms to the medium during manipulations. At the 

 inner side of the rubber stopper that is, the end which is 

 to be inserted into the test-tube the glass tubes are of 



