298 



BACTERIOLOGY 



= Complement 



Immune body 



Antigen 



Fig. 58 



Factors present and in combination in un- 

 heated immune serum to which antigen 

 has been added. Reaction complete. 



In the hemolytic system it is obvious, in so far as two 

 factors are concerned, that specific relationship is essential 

 to the reaction. Thus, immune serum from an animal 

 immunized from sheep's blood possesses amboceptors specific 

 for the sheep's blood corpuscles and none for the corpuscles 

 of other animals, so that if to such immune serum blood cor- 

 puscles other than those of the sheep be added, no hemolysis 

 occurs, even though it may have been conspicuously active 

 for sheep's corpuscles. 



The relationship of the complement to the amboceptor and 

 antigen is not specific. It reacts with any or all amboceptors 

 and antigens and is present in all mammalian blood. 



It must not be forgotton, as stated above, that natural 

 hemolytic activity is sometimes exhibited by one blood for 

 another, consequently, in arranging studies in this field 

 this fact should be borne in mind and care exercised to con- 

 trol all experiments. 



FIXATION OF COMPLEMENT. 



From the investigations of Bordet and Gengu upon the 

 relations between antibodies and complement, methods have 

 been developed by which it is possible to detect very small 

 quantities of antibodies in fluids under question on the one 



