BACTERIOLYSIS S. 1 1 7 



bacilli absorb or bind less agglutinin than "nor- 

 mal" strains (Miiller, Cole, Eisenberg). Explained 

 in terms of Ehrlich's theory, it is assumed that 

 they contain a decreased number of binding 

 molecules or receptors for the agglutinin, hence an 

 effective quantity of the latter is not bound. 



Experiments by many observers indicate that Resistance to 



, r . , J r Bacterio- 



bacteria may also acquire resistance to the bac- 

 tericidal action of the serum, and that this prop- 

 erty goes hand in hand, at least to a certain extent, 

 with the virulence of the micro-organism. In some 

 of these experiments the resistance has been 

 acquired by growing the organisms in the corre- 

 sponding antiserum, for a greater or less length 

 of time. Thus Cohn, by growing the typhoid 

 bacillus on antityphoid serum, conferred on it an 

 increased resistance to bacteriolysis, which was 

 retained for several subsequent generations on agar. 

 Day also, in a similar way, caused increased serum 

 resistance in B. prodigiosus, B. vulgaris and B. 

 ftuorescens, and even conferred some pathogenic 

 powers on these organisms, which naturally are 

 rather harmless saprophytes. 1 Such results have 

 been obtained with the organisms of typhoid 

 (Walker, Haffkine and others), cholera (Szekely, 

 Kansom, Kitashima and others), dysentery (Mar- 

 shall, Knox, Mason), anthrax (Shaw, Danyz and 

 others), the colon bacillus (Hamburger), Vibrio 

 metclmikovi (Metchnikoff, Bordet and others). It 

 has frequently been found also that bacteria when 

 freshly cultivated from infections have an 

 unusually high resistance to the bactericidal action 

 of serums. Besserer and Jaffe noted that a strain 



1. Eisenberg gives a summary of this and kindred subjects 

 in the Centralbl. f. Bakteriol., etc., xlv, No. 2. 



