SO THE MECHANISM OF AGGLUTINATION, 



coli commune was distributed in a small portion of the filtrate. 

 This suspension was treated with active typhoid serum in the 

 proportion of 20 parts of suspension to 1 of the serum. The 

 bacteria, which before the addition of the active serum had been 

 uniformly distributed in the Bact. typhi filtrate, had after an 

 hour become collected into clumps. As it seemed possible that 

 some objection might be made to the use of Bact. coli commune 

 on the ground that the serum might have been obtained from a 

 case of mixed Bad. typhi and Bact. coli comnune infection, a 

 second experiment was made with Bact. Hartlebii. Agglutination 

 occurred precisely as when Bad. coli commune had been employed . 

 These experiments show that Gruber's and Radzievsky's objec- 

 tions are groundless, and they are in agreement with Nicolle's, 

 who showed that foreign bacteria suspended in the filtrate of a 

 Bact. typhi culture were agglutinated by active sera. 



Since agglutination is essentially the coagulation of a precipitate, 

 it will be prevented by the presence of anti-coagulating agents 

 such as the alkaline citrates and acetates. Winterberg (9) in a 

 recent paper showed that the scvcalled agglutinines were destroyed 

 by acetates, as evidenced by the absence of clumping. It is clear 

 that the non-clumping was due to the acetates preventing the 

 flocculating action of the serum and bouillon salts and not to the 

 destruction of the enzyme. 



Although bacteria are not flocculated b}' salts like inorganic 

 particles, it seemed possible that they might be induced to 

 simulate flocculation by causing a silver compound to be formed 

 upon the outer surface of the cells. With this object in view, 

 bouillon cultures of Bact. typhi, Bact. coli commune, and Bad. 

 prodigiosum were filtered through Kitasato filters, washed with 

 sterile distilled water and finally suspended in distilled water. 

 Again, cultures of these three organisms were scraped from an 

 agar surface and suspended in distilled water. All the suspen- 

 sions were gently centrifuged to eliminate clumps and to obtain 

 a uniform suspension of the bacteria. The suspension was then 

 treated with a few drops of - 5 % silver nitrate (a quantity which 

 was in excess as far as chlorides were concerned) and centrifuged 



