INFECTION . AND RESISTANCE 



agglutinative characteristics induced in bacteria when they become 

 parasitic upon different hosts, and Smith and Reagh conclude that 

 such changes of parasitic habitat may modify the agglutinative prop- 

 erties (probably by adaptation to the peculiar reactions of each host), 

 some of them being weakened and others strengthened. 



The animal species used for immunization indeed influences the 

 quantity and nature of the produced agglutinin considerably. For 

 instance, in Pfeiffer's 42 experiments, a dog, a chicken, and a rabbit 

 were immunized with the same strain of cholera spirilla. The 

 sera obtained from these animals agglutinated this and other strains 

 of cholera spirilla in an entirely irregular manner showing that 

 the constitution of the agglutinins in each case was an absolutely 

 different one in regard to the relative concentrations of "major" and 

 "minor" constituents. 



Castellani 43 found that the immunization of an animal with 

 two or more different species of bacteria results in the formation of 

 agglutinins against all of these. Supposing, for instance, that species 

 A and B are used for treatment, agglutinins against both A and B 

 are formed in quantity, depending upon the intensity of the treat- 

 ment in each case. N"ow, if to the serum so produced. an emulsion of 

 A is added, agglutinin A only will be removed, while agglutinin B 

 will remain in the serum almost undiminished. An example of this 

 is seen in the following protocol taken from Castellani' s paper : 



In the preceding paragraphs, however, we have seen that im- 

 munization with a single organism, say B. typhosus, will induce the 

 formation of agglutinins, not only for this species, but also of para 

 or minor agglutinins for biologically similar strains as well. In 

 such cases, as Castellani showed, absorption of the serum with the 

 organism used for immunization takes out, not only the major ag- 

 glutinins, but rather all of the agglutinins, major and minor. Con- 

 versely, however, absorption of such a serum with the species ag- 

 glutinated by the minor agglutinins takes out these antibodies only, 

 leaving the major substances intact. These relations are well illus- 



42 Pfeiffer. Quoted from Paltauf in "Kolle u. Wassermann Handbuch," 

 Vol. 4. 



43 Castellani. Zeitschr. f. Ilyg., Vol. 40, 1902. 



