BACTERICIDAL PROPERTIES OF BLOOD SERUM 163 



laws of definite proportion, an idea which still underlies, though 

 somewhat loosely, many of the more important views of antigen- 

 antibody reactions as conceived on the basis of the amboceptor theory. 



Gay has suggested also that the Neisser-Wechsberg phenomenon 

 may well be explicable on the basis of the fixation of complement by 

 precipitates. In a succeeding section we will discuss the fixation of 

 alexin, which occurs when a dissolved protein is brought together 

 with its specific antiserum. It is not impossible that this may occur 

 when bacterial emulsions, from which a small amount of bacterial 

 protein may well go into solution, are brought together with anti- 

 serum in concentration. Under such conditions a reaction might 

 readily occur which would lead to the fixation of alexin and its con- 

 sequent deviation from the sensitized bacteria. 



Of all explanations considered, therefore, that of Neisser and 

 Wechsberg seems to be the least likely. It would seem to us that 

 Bordet's interpretation of these facts is borne out indirectly by cer- 

 tain experiments of Morgenroth and Sachs 5T themselves, in which 

 the mutual quantitative relations between complement and "ambo- 

 ceptor" were studied. In these experiments it was shown that the 

 more highly cells were sensitized, the smaller was the quantity of 

 complement which was needed for their hemolysis, and vice versa, 

 the less the sensitization (the smaller the quantity of amboceptor) 

 the more complement was necessary to produce the same result. 

 The following extract from one of their protocols will illustrate this : 



BEEF BLOOD CELLS 5%, 1 C. C., ANTIBEEF GOAT SERUM, GUINEA-PIG COMPLEMENT 



A similar relation may be observed by all who have occasion to 

 work with hemolytic reactions. In the present connection this seems 

 to bear out Bordet's interpretation, since, knowing the differences in 

 functional efficiency of various complements for different hemolytic 

 and bactericidal complexes, we could well expect that insufficient 

 sensitization of a red cell or bacterial antigen, not particularly amen- 

 able to the complement employed, might fail to absorb it completely 

 out of the serum, thus giving a negative result which would simulate 

 complete lack of affinity. 



This research of Morgenroth and Sachs seems further of funda- 

 57 Morgenroth and Sachs. Berl kl. Woch., No. 35, 1902. 



