AGGLUTININS AND PRECIPITINS 87 



emulsion of typhosus and 0.5 c.c. thin emulsion colon. After incubation only 

 tube i shows agglutination, because the colon agglutinins have been ab- 

 sorbed. The protocol of this experiment with the controls follows: 



SERIES A (ABSORBED BY TYPHOSUS) 



1. Fluid A 0.5 c.c. -j- 0.5 c.c. typhosus = no agglutination. 



2. Fluid A 0.5 c.c. T 0.5 c.c. colon = agglutination. 



SERIES B (ABSORBED BY COLON) 



3. Fluid B 0.5 c.c. + 0.5 c.c. typhosus = agglutination. 



4. Fluid B 0.5 c.c. + 0.5 c.c. colon = no agglutination. 



CONTROLS 



5. Saline 0.5 c.c. + 0.5 c.c. typhosus = no agglutination. 



6. Saline 0.5 c.c. + 0.5 c.c. color no agglutination. 



This experiment shows only the essentials of the specific absorption. It 

 may be further elaborated by making a series of dilutions of the treated 

 serum so as to show the fact that the titer is essentially unimpaired. 



Result 



Result 

 + 



This experiment shows that the process of absorption removes 

 only the specific agglutinin and leaves the other agglutinin un- 

 changed. As a matter of practical fact, the typhoid agglutinin re- 

 mains unchanged, but the colon agglutinin may be somewhat reduced 

 in titer, perhaps to 1-800 or even as low as 1-300. In a combined 

 serum of this sort with the typhoid agglutinin of high titer, part of 

 the agglutinin for colon is the result of a typhoid minor agglutinin 

 which is removed by absorption with typhosus, thus reducing the 



