PAUL H. De KRUIF 



391 



It will be noted that the acid agglutination optimum for Microbe 

 D is the same in case of all three of the strains tested. On the other 

 hand, the optimum for Microbe G varies to a considerable extent. 

 This variation is never so great as to prejudice its value as a criterion 

 of differentiation from the parent D form. In all cases complete 

 flocculation of Type G occurs at a distinctly lower Ch"*" than that of 

 Type D. The difference between the two types in regard to the 

 smallest amount of hydrogen ion in which complete flocculation 

 takes place is never less than 0.6 pH. In short, the organism in the 

 process of mutation gains in sensitivity to flocculation in the presence 

 of H ions. 



TABLE V. 



Acid Agglutination Optima of D and their Mutant G Forms, 

 Na Acetate-Acetic Acid Series. 



* G-S 28, a mutant from the same parent D strain as G-S 52. 



Sobernheim and Sehgmann (5) found a strain of Bacillus enler- 

 itidis to separate into two races. Beniasch (4) tested the acid ag- 

 glutination point of this organism and found it to have altered its 

 acid agglutination optimum when tested on two different occasions, 

 a year having elapsed between the two tests. In this work apparently 

 no attempt was made to establish the occurrence of a mutation, or 

 to separate the two varieties. 



