Immunity against micro-organisms 319 



after the injection this fluid became more and more rich in leucocytes 

 which seized the vibrios, ingested and destroyed them. To obtain 

 this protective effect it was necessary to inject from O'l to 5 c.c. of 

 human blood serum. With these doses he could prevent, not only 

 infection of the guinea-pigs by the cholera vibrio, but also the lethal 

 effects of other vibrios. The protective action of normal human serum 

 is general, therefore, and not specific, such as is the immunity conferred 

 by the serums of vaccinated animals or of the human subject who has 

 suffered from an attack of cholera. 



Shortly afterwards Funck^ confirmed this result in the case of the [335] 

 typhoid cocco-bacillus. He observed that normal horse's serum, in- 

 jected as a protective agent in the dose of half a c.c. into the peritoneal 

 cavity of the guinea-pig, preserved this animal from a fatal infection. 

 Pfeiffer and Kolle and Chantemesse and Widal obtained the same 

 results with human serum. The former observers lay special stress 

 on the non-specific character of this protective action of normal 

 serums. As to its mechanism, Funck sums it up as follows : " the 

 specific serum brings about a rapid lysis of the bacilli, normal serum 

 acts in a much more limited fashion ; if the dose is very large and 

 if the animal resists infection, the phenomena of extracellular de- 

 generation are rarely appreciable, and it seems that here the specially 

 important factor is the intracellular destruction of the bacteria, in the 

 phagocytes " (p. 70). 



Wassermann has shown the protective action of normal serum 

 against the experimental disease produced by the staphylococcus. 

 This action, although not absolutely general, is nevertheless widely 

 distributed. Wassermann 2, from comparative investigations on this 

 subject, came to the conclusion that " the serum of a different species 

 of animal acts by greatly increasing the resistance, whilst the serum 

 of the same species produces an effect which is not nearly so marked." 

 As in these normal serums a stimulating influence on the phagocytes 

 is specially marked, it may readily be understood that the serum of 

 the same animal or of the same species does not produce so energetic 

 an effect as the serum of a different species. As these normal serums 

 possess, not only the property of exciting phagocytosis, but often also 

 that of rendering motionless and of agglutinating certain micro-organ- 

 isms, there might be some difiiculty in interpreting the part played 



1 "La Serotherapie de la fi^vre typhoide," Bruxelles, 1896, p. 69. 



2 Ztschr.f. Hyg., Leipzig, 1901, Bd. xxxvii, S. 199. 



