GROWTH OF CERTAIN ANAEROBES 



423 



the curves of growth in relation to hydrogen ion concentration 

 are almost identical for all the anaerobes studied. When compar- 

 ing these curves with those given before for the pneumococcus 

 and diphtheria bacillus (Dernby and Avery, 1918, Dernby and 

 David, 1920), it is obvious that they are much broader, with limits 

 from pH 5 to pH 9, whereas the limits for the pneumococcus 

 are pH 7 to pH 8.3 and for the diphtheria bacillus pH 5.5 to 

 pH 8. Obviously the hydrogen ion concentration has much 



TABLE 4 

 Growth of four types of anaerobes 

 Strains used: 1. Clostridium sporogenes A. (Klein-Metchnikoff) 



2. Clostridium canadiense 



3. Clostriditim putrijicum (BienstocR) 



4. Clostridium perfringens (Veillon and Zuber) 

 Time of incubation, seventeen hours. Temperature, 37° 



less influence — within certaia limits — on the growth of these 

 anaerobes than on the growth of, e.g., the pneumococcus. 



The optimum for all of the microorganisms studied here seems 

 to fall between pH 6.5 and pH 7.5. If any distinction should 

 be made it might be said that Clostridium sporogenes seems to 

 have an optimum a little less than pH 7 and the others a little 

 more than pH 7. That indicates that these microorganisms 

 grow most favorably in media which have a neutral reaction, 

 that is pH 7. 



