ANTIBACTERIAL SERUMS. 375 



the intestines are a reservoir of typhoid bacilli, 

 although the living organisms reach the circula- 

 tion in abundance. 



By way of summary, the following conditions 

 appear as factors in the low curative value of bac- 

 tericidal serums: 1. Bactericidal serums are not 

 antitoxic. 2. They may liberate an excessive 

 amount of endotoxin by dissolving the bacteria. 3. 

 The lability of exogenous complement. 4. The 

 power of the tissues to absorb the complements of 

 a foreign serum. 5. The lack of a sufficient 

 amount of suitable complement in the human 

 body. 6. The difficulty of obtaining amboceptors 

 for which human complements are suited. 7. The 

 possibility of diversion of complement by an ex- 

 cess of amboceptors. 8. Inaccessibility of the 

 micro-organisms in certain infections (cholera, 

 typhoid). 



As pointed out elsewhere, another group of or- other "An 



bacterial" 



ganisms, the members of which contain endo- serums. 

 toxins, causes the formation neither of antitoxins 

 nor of bactericidal serums; streptococcus, staphy- 

 lococcus, pneumococcus, etc. Many investigators, 

 nevertheless, are positive in their claims that the 

 antiserums for these organisms have a protective 

 and even a curative value. The properties on which 

 their value depends have not been satisfactorily 

 ascertained. Although certain antistreptococcus 

 serums are said to be antitoxic, it is contended by 

 others that they act by stimulating phagocytosis. 

 It has been shown that immunization with these 

 organisms causes an increase in the opsonins. 

 Their curative value is very low in experimental 

 work and they fail totally if injected a few hours 



