FURTHER STUDIES ON THE DYSENTERY BACILLUS. 321 



centrifuging, washing the bacilli from those tubes in which no agglu- 

 tination had occurred, and adding to them a dose of agglutinin which 

 by itself would suffice for agglutination. The result was that these 

 bacilli always showed themselves to be no longer agglu tillable, 

 see (Table VII.) 



TABLE VI. 



One other point may be mentioned. In the experiments thus 

 far described the quantity of bacteria was the same in all the tubes 

 (See above.) However, if the amount was greatly increased, other 

 phenomena were observed. Table VIII shows that the zone of 

 proagglutinoid disappears entirely if a sufficiently large quantity of 

 bacteria are employed. 



The explanation of this phenomenon is not difficult if we bear 

 in mind the experiments of M. Neisser and Lubowsky 1 on the one 

 hand and those of Eisenberg and Volk on the other. The experiments 

 of the latter show without doubt that typhoid bacilli, for example, 

 are able to anchor a far greater quantity of agglutinin than is required 

 for their agglutination. One may therefore assume that the dysentery 

 bacillus also possesses a large number of receptors which are able to 

 unite with, i.e. anchor, the proagglutinoid. The occupation of only a, 

 few of these many receptors by the active agglutinin is apparently 

 sufficient, however, to agglutinate the dysentery bacillus. Hence if 

 we add comparatively few dysentery bacilli to a serum which contains 

 much proagglutinoid and little agglu tinin, a large number of receptors 

 of the bacilli will be occupied by proagglutinoid. If, on the contrary, 



1 See pages 146 et seq. 



