THE STUDY OF OBLIGATELY ANAEROBIC BACTERIA iii„-7 



method in almost any laboratory at any time. The technic is so simple that no 

 previous experience with the method is necessary for success. Since each set of plates 

 is an individual unit, observation of the growth of the anaerobe may be made at any 

 time without destroying the anaerobic conditions. Disadvantages: It is somewhat 

 time-consuming when large numbers of platings are to be made, and, therefore, not 

 suitable in laboratories where routine plating of a number of cultures is not an unusual 

 event. Anaerobic conditions may not be attained sufficiently quickly to prevent 

 death of the inoculum of non-spore-forming species or vegetative cells of anaerobic 

 spore formers. 



Method B 



Materials for method similar to that of Marshall and Nordby 

 (1942) : (1) One petri plate of usual size (bottom should be 15 mm. 

 deep); (2) one small petri plate" (75 mm. X 10 mm.); (3) culture 

 of »S. marcescens; (4) tube of nutrient agar. 



Method: Pour nutrient agar in bottom half of the regular size 

 plate, and streak or flood surface with aerobe. Pour agar for anaerobe 

 in bottom half of small plate. Remove this bottom from its top and 

 press down in agar of the regular size dish. 



Advantages: A simple method suitable for small numbers of plates. The pur- 

 chase of the small-sized plates is less expensive than some of the more elaborate ap- 

 paratus required by certain other methods. Disadvantages: Necessity of purchase 

 of the small-sized jilates. 



Chemical Methods for Oxygen Removal 

 Many of the methods proposed for removal of oxygen from the 

 environment for anaerobic culture involve the initiation of a chemical 

 reaction in which oxygen is consumed. Of the various systems 

 which have been suggested, those which are recommended have been 

 tested and used sufficiently to show their utility and do not require 

 elaborate apparatus. 



PHOSPHORUS JAR 



Materials: (1) Sticks of yellow (or white) phosphorus (which 

 must be kept under water in tightly stoppered wide mouth bottle; the 

 small sticks, y^ inch diameter, are the most useful); (2) Pyrex 

 cylinder or any convenient jar or container which may be sealed 

 air tight; (3) pair of long forceps or chemical tongs; (4) plasticene; 

 (5) small amount of tap water. 



Method: Place small amount of tap water in bottom of cylinder 

 to remove the P2O6 which forms. Stack inoculated plates or tubes 

 on support. Add tube of methylene blue solution (see p. 11143-5). 

 Place small (50 ml.) beaker on top of cultures. Remove two or 

 three short {\}/2 to 2 inch) pieces of phosphorus from water with 

 forceps or tongs and place in beaker. Immediately put lid on jar 

 and seal with plasticene. (Upon drying for a few minutes, the 

 phosphorus should ignite spontaneously and remain burning as 

 long as there is oxygen present). If experience shows that the 



^Small petri plates. Central Scientific Company, Chicago. Illinois. 



