FURTHER STUDIES ON THE DYSENTERY BACILLUS. 323 



we add a large quantity of bacteria to the same amount of serum, the 

 proagglutinoid will not suffice to occupy all the receptors and some 

 agglutinin will be enabled to combine with the bacteria. This, how- 

 ever, results in agglutination. 



As already mentioned, my original culture proved entirely identical 

 with the Kruse culture so far as the zone of proagglutinoid was con- 

 cerned. The Flexner culture, on the contrary, behaved differently, 

 for, although it was agglutinated in the same degree by the immune 

 serum, the zone of proagglutinoid was entirely absent. This is well 

 shown in the following table. 



TABLE IX. 



Absorption tests, which were then made, showed that the Kruse 

 bacillus when added to my immune serum completely abstracted the 

 agglutinin and proagglutinoid for this strain, while the agglutinin for 

 the Flexner strain was abstracted to only a slight degree. Conversely, 

 when the Flexner bacillus was added to my immune serum and the 

 mixture centrifuged it was found that the agglutinin for Flexner 's 

 bacilli had been completely absorbed, but only a small part of the 

 agglutinin and proagglutinoid for the Kruse strain. 



We shall therefore have to assume that my original strain corre- 

 sponds completely to the Kruse strain so far as the receptor apparatus 

 is concerned, while both these strains possess certain receptors identical 

 with those of Flexner's strain, and others which differ from them. 

 We may furthermore assume that the serum with which these experi- 

 ments were made was obtained by immunizing not only with my 

 original strain, but that in the course of years various other strains 

 had been used for immunization. In this way agglutinins of various 

 kinds were developed, and these, of course, also fitted strains w T ith 



