450 HILDA HEMPL HELLER 



III. To separate either variety of anaerobes from sporulating 



aerobes 



Sporulating aerobes are rather infrequently found in patho- 

 logical material. One meets them frequently, however, in a me- 

 dium that has been insufficiently sterilized. My encounters with 

 sporulating aerobes have been so rare that it would be wise to 

 recommend that a worker always go back to the original material 

 and test it for the presence of any sporulating aerobe that he finds 

 in a culture with which he is working. Avoid sporulating aerobes, 

 do not contaminate cultures with them, and isolate the anaerobes 

 from the original material again. 



1. Sporulating aerobes are of two classes: strict aerobes (any 

 good anaerobic technique followed by a colony method will free a 

 culture of these) and facultative anaerobes. I have never en- 

 countered a sporulating facultatively-anaerobic aerobe that grew 

 better under strictly anaerobic conditions than its accompanying 

 anaerobes. Any strictly anaerobic colony method that will sep- 

 arate anaerobes from each other will separate them from aerobes. 

 In my experience trouble with abundantly growing aerobic organ- 

 isms denotes faulty anaerobiosis : the presence of a small amount 

 of oxygen that permits the undue multiphcation of the aerobes. 

 My experience has, however, been almost entirely with patho- 

 logical material and I may have failed to meet with the most 

 troublesome aerobic organisms. 



2. Kitasato and Weyl found that anaerobes were less sen- 

 sitive to pyrocatechin, chinon, sodium formate, and sodium sul- 

 phindigotate than were the aerobes causative of cholera, typhoid 

 and anthrax. Rivas continued this type of investigation. 



3. Churchman has investigated the inhibitive effect of gentian 

 violet on aerobic growth. Hall recommends the use of gentian 

 violet in a dilution of 1 :100,000 to separate sporulating aerobes 

 from anaerobes. This, I should think, would work very well for 

 the heavy Gram positive organisms of the B. subtilis group, pro- 

 vided the desired anaerobe is not of the same nature. 



4. The spores of aerobes may sometimes be satisfactorily ger- 

 minated in broth in a Petri dish, the broth being then heated and 

 inoculated into agar. 



