396 PATHOGENIC MICROORGANISMS 



bacteriolysis may occasionally be demonstrated in the serum of normal 

 individuals. 



Agglutinins for the colon bacillus have often been produced in the 

 sera of immunized animals in concentration sufficient to be active in dilu- 

 tions of 1 : 5,000 and over. The agglutinins are produced equally well 

 by the injection of live cultures and of those killed by heat, if the tem- 

 perature used for sterilization does not exceed 100° C. It is' a notice- 



12 3 



Fig. 84. — ^Bacillus coli communis. Grown in: 1. Dextrose, 2. Lactose, 3. 

 Saccharose broth. The bacillus forms acid and gas from dextrose and lactose, 

 not from saccharose. Note the absence of growth in the closed arm of the sac- 

 charose tube, in which no acid or gas is formed. 



able fact that the injection of any specific race of colon bacilli 

 produces, in the immunized animal, high agglutination values only for 

 the individual culture used for immunization, while other strains of 

 colon baciUi, although agglutinated by the serum in higher dilution 

 than are paratyphoid or typhoid bacilli, require much higher concen- 

 tration than does the original strain. The subject has been extensively 

 studied by a number of observers and illustrates the extreme individual 



Wolff, Cent. f. Bakt., xxv, 1899. 



