\.\TURE OF SUBSTA\r/;s CONCERNED L\ T AGGLl'TI \ \TIOX 181 



Similar conditions to those noted in previous chart, except that a young goat has been used for the 

 injections of the colon bacillus X. The great accumulation of common agglutinins for the para- 

 dysentery bacillus in the third month of the injections of the bacillus X is very striking. 



Tests made. 



The Use of Absorption Methods for Differentiation between Specific 

 and Group Agglutinins due to Mixed Infection and to a Single Infection. 

 It is now well established that if an infection is due to one micro-organ- 

 ism there will be specific agglutinins for that organism and group- 

 agglutinins for that and other more or less allied organisms. If infec- 

 tion is due to two or more varieties of bacteria, there will be specific 

 agglutinins for each of the micro-organisms and group agglutinins 

 produced because of each of them. 



The above facts have been demonstrated by several investigators. 

 The following experiments selected from those reported by Castellani 1 

 well illustrate these points: A rabbit immunized to B. typhi agglu- 

 tinated B. typhi 1:5000, B. coli (31) 1:600. After saturation with B. 

 typhi all agglutinins were removed for both micro-organisms. A rabbit 

 immunized to both B. typhi and B. coli (31) agglutinated B. typhi 

 1 : 4000, B. coli (31) 1 : 1000. (After saturation with B. typhi the serum 

 did not agglutinate B. typhi, but B. coli (31) 1:900.) After saturation 

 with B. coli it failed to agglutinate B. coli (31), but still agglutinated 

 B. typhi 1:4000. 



From these and other experiments Castellani drew the important 

 conclusions : 



1. The serum of an animal immunized against a certain micro- 

 organism, when saturated with that micro-organism, loses not only 

 its agglutinating power for that organism, but also for all other varieties 

 that it formerly acted upon. Saturated with the others, its action upon 

 the first is reduced little or not at all. 



2. The serum of an animal immunized against two micro-organisms, 

 A and B, loses its agglutination when saturated with A only for A. 

 Saturated with A and B it loses its agglutinating power for both. 



3. These facts may be applied to the diagnosis of an unknown mixed 



i Zeitschrift f. Hyg., Bd. atl., 8. 17. 



