72 STUDIES IN IMMUNITY. 



killed by diphtheria toxin, both produce the phenomenon; in these 

 latter fluids numbers of leucocytes are present. 



Hanging drops. 



Cholera (Eastern Prussia) -f normal G. p. serum. 



+ preventive goat serum + normal G. p. serum. 



preventive goat serum + normal goat milk 



4- preventive goat serum + human urine. 



+ preventive goat serum + human tears 



+ preventive goat serum -f human saliva 



+ preventive goat serum + G. p. aqueous humor. 



+ preventive goat serum + edema anthrax G. p. 



preventive goat serum + pleural ex. dipt. G. p. . 



What is the action of edema fluid from a guinea-pig that has been 

 highly immunized against cholera? It is known that fresh serum 

 from this animal will alone produce the phenomenon, since it con- 

 tains both the bactericidal and the preventive substances. It is 

 therefore of interest to determine whether the edema fluid from 

 such a guinea-pig will lack one or both of these substances. Edema 

 fluid alone, without either normal serum or preventive serum, does 

 not cause the phenomenon. But are both substances or is only 

 one of them lacking? To determine whether the bactericidal 

 substance is lacking, a hanging drop is prepared containing the 

 vibrio, preventive serum and edema fluid. Controls are made as 

 indicated. 



Hangin, drops. 



Cholera (Eastern Prussia) + normal G. p. serum 



-f preventive goat serum + normal G. p. serum 



+ preventive goat serum + vaccinated G. p. edema. . . . 



From this table it is evident that the edema fluid from immunized 

 animals as well as that from normal animals contains no demon- 

 strable bactericidal substance. But is the preventive substance 

 entirely lacking? It will be recalled that in previous experiments 

 the edema fluid was shown to be distinctly preventive for animals 

 although inferior in this respect to serum. In the following table 



