204 PUBLIC HEALTH BACTERIOLOGY 



wondered at considering the enormously increased and 

 increasing complexity of the subject-matter. 



Under either theory of immunity, the immune-body 

 produced in active immunization is specific, that is, there 

 is a special immune-body produced for each antigen. On 

 the other hand, the complement, or alexine, or cytase, is 

 believed to be one and the same, though Ehrlich and his 

 school have argued in favour of specific complements for 

 specific amboceptors. 



FURTHER IMMUNITY PHENOMENA. 



These can be more easily followed after the terms used 

 in the theories have been acquired. 



i. Filtration of Serum. Muir and Browning found 

 that on filtering serum through a Chamberland bougie, the 

 immune-body passed through, and the complement did not. 



2. Fixation of the Complement. Bordet and Gengou 

 planned an experiment, called the M Bordet and Gengou 

 Reaction," to demonstrate the presence in a given serum 

 of a specific immune-body, even in very small quantities. 

 To this reaction the term " Fixation of the Comple- 

 ment " is now commonly applied, and has its best known 

 practical use in the " Wassermann Reaction." They 

 performed two parallel experiments, (i) and (2), in which 

 they used the following mixtures : 



(1). Heated immune plague serum -f plague bacilli 

 emulsion -f fresh normal serum. 



(2). Heated normal serum + plague bacilli emulsion -f- 

 fresh normal serum. 



Set aside for five hours at blood heat. Then added to 

 each mixture : 



(a) geated hemolytic serum + washed red blood cells. 



Obs*e?v^ results : Mixture (1) shows no haemolysis ; 

 mixture (2) shows haemolysis. 



The explanation of this phenomenon is after this 

 manner : Looking at (a) we see that the mixture there 

 requires the addition of complement to produce haemolysis, 

 since the complement in the serum has been destroyed by 

 heat. Therefore, when mixture (2) produces haemolysis, 

 we infer that it must have supplied complement ; and 



