PAUL H. De KRUIF 



399 



concentration of beef infusion demands a higher Ch+ than in the case 

 of Type G. For each organism the range of Ch"*" at which the small- 

 est amount of beef infusion is required for complete sedimentation is 

 precisely the optimum zone of acid agglutination described in the 

 preceding paper. 



The results of the experiments recorded in Tables II and III are 

 represented graphically in Fig, 2, in which the pH of the various dilu- 

 tions of beef infusion are plotted on the abscissae against the recip- 



TABLE III. 

 Beef Infusion Agglutination of Microbe D at Varying Ch+. 



rocals of the amount of beef infusion on the ordinates. That is, 1.0 

 cc. of beef infusion is represented by 1, 0.5 cc, by 2, 0.5 cc. by 4, 

 and so on. The points recorded on the graphs are in all cases the 

 amounts of beef infusion which cause complete flocculation, represented 

 by C, Tables II and III. 



The graphs of Fig. 2 would seem to afford an explanation for the 

 granular growth of Microbe G and the diffuse growth of Microbe D 

 in broth, since at pH 7.0, the Ch+ at which these organisms are 

 grown, large amounts of beef infusion cause complete sedimentation 

 of Microbe G and Httle or no agglutination of Microbe D. 



What is more, the graphs would appear to indicate that beef in- 

 fusion, per se, does not cause the agglutination. It merely widens the 



