IMMUNITY AND SUSCEPTIBILITY. 77 



encased produce an inflammatory transudate which may 

 have properties very different from those of the normal 

 juices. 



How much of the immunity which animals enjoy de- 

 pends upon the antibactericidal action of their body- 

 juices must remain an open question. In some cases the 

 germicidal action of the blood seems to be unquestion- 

 able. Buchner has shown that the blood-serum of ani- 

 mals only possesses this germicidal power when freshly 

 drawn, and that exposure of the serum to sunlight, its 

 mixture with the serum from another species of animal, 

 its mixture with distilled water or with dissolved cor- 

 puscles, and heating it to 55 C., check the bactericidal 

 power. Buchner also points out that the bactericidal 

 and globulicidal actions of the blood are simultaneously 

 extinguished. Meltzer and Norris 1 found that lymph 

 taken from the thoracic duct of the dog possessed marked 

 bactericidal powers upon the typhoid bacillus. 



The experiments of Pfeiffer seem to add additional 

 support to the humoral theory of immunity. He found 

 that when guinea-pigs were given experimental choleraic 

 peritonitis, they could be saved from death from the affec- 

 tion by intraperitoneal injection of serum from an 

 immunized animal. He also showed that when the cul- 

 ture of cholera, or a culture cf typhoid bacilli, was in- 

 jected into the peritoneum of a guinea-pig, the multipli- 

 cation of the bacteria was rapid. If, however, a few 

 drops of the immunized serum were introduced, a marked 

 effect was observed, for the serum seemed to exert a 

 germicidal effect upon the bacteria, and transform them 

 from living entities into inanimate little granular masses. 



Hankin is of the opinion that the germicidal sub- 

 stances of the blood-serum are derived from the eosinophile 

 cells, and resides in the matter forming the eosin-granules. 



Lowit, 2 in investigating the bactericidal power of the 



1 Journal of Experimental Medicine, vol. ii., No. 6, p. 701, Nov., 1897. 



2 Bietrage zur Pathol. Anatomic und zur Allgem. Pathologic, Bd. xxil., H. 

 I, P- 173- 



