106 IMMUNE SERA 



gested, the complements present in human serum 

 may not be able to reactivate immune bodies 

 derived from the horse, sheep, or other animal 

 furnishing the therapeutic serum. Probably the 

 most important cause of the failure of these sera 

 is that they do not reach the bacteria in the body. 

 In the case of cholera, for example, it is hardly to 

 be expected that the serum injected would affect 

 the spirilla, for most of these are in the intestinal 

 contents, and therefore really outside of the body. 

 In many of the bacterial infections the organisms 

 accumulate in the lymph glands and other sites 

 where they cannot readily be reached by anti- 

 bodies circulating in the blood. Instructive in this 

 connection are the good results achieved by intra- 

 spinal injections of antimeningococcus serum, when 

 exactly the same serum had proven valueless when 

 given subcutaneously. 



