BACTERICIDAL SERUMS. 371 



atives, cause the development of strong bacterici- 

 dal serums in the immunized animal. In Chapter 

 XVI, A, it was shown that such serums have no 

 power of neutralizing the endotoxins of the corre- 

 sponding organisms; hence, whatever prophylactic 

 and curative properties they may have would seem 

 to depend on the bactericidal action of the ambo- 

 ceptor-complement complex. As to whether the 

 substances which stimulate phagocytosis, i. e., the 

 opsonic or bacteriotropic substances are of impor- 

 tance for the intra vitam action of bactericidal 

 serums, remains to be definitely established. 



It is common knowledge that bactericidal curative 

 serums have not been successful curative agents, 

 although in test-glass experiments they may be 

 able to kill large numbers of organisms. Experi- 

 mental work has brought to light a number of con- 

 ditions which render their ineffectiveness some- 

 what intelligible, but this knowledge has been of 

 little service in increasing their value, and at this 

 moment their outlook as curative agents is not very 

 encouraging. 



Animal experiments indicate that, prophylacti- 

 cally, they are much more powerful than when 

 used as curative agents. Unfortunately, however, 

 as in the case of antitoxins, the immunity which is 

 conferred is of short duration, the serum being ex- 

 creted or the antibodies destroyed within two or 

 three weeks. For this reason they are not suited 

 for general prophylactic use in man, but they may 

 be distinctly useful when combined with vaccina- 

 tion, as indicated later. 



Bactericidal serums are efficient in saving ex- Time of 

 periment animals, provided the serum is injected InJe< 

 in advance of, simultaneously with or very shortly 



