474 BACTERIOLOGY. 



A striking illustration of this protective reaction on 

 the part of the animal tissues is brought out in the 

 course of R. Pfeiffer's' experiments on Asiatic cholera. 

 He found that it was possible to confer immunity to 

 animals from this disease; that the blood-serum of such 

 animals protected susceptible animals into which it was 

 injected against what would otherwise be a fatal dose of 

 the cholera spirillum; that the peritoneal fluids of the 

 artificially immunized animal had an almost instantane- 

 ous disintegrating, bactericidal action upon living cholera 

 spirilla that were injected into the peritoneal cavity; that 

 the serum from the immune animal had no such effect 

 upon cholera spirilla when tried in the test-tube; but if 

 virulent cholera spirilla be injected into the peritoneum 

 of an animal that was not immune, and this be at once 

 followed by an intraperitoneal injection of serum from 

 an immune animal, almost instantly the peculiar dis- 

 integration of the bacteria, as observed in the perito- 

 neum of the immune animal, could be detected. This 

 latter observation is of the utmost importance in its 

 bearing on Buchner's hypothesis, for we see here a 

 serum from an immune animal that is capable of 

 conferring immunity; capable, on injection into a sus- 

 ceptible animal, of endowing its fluids with the peculiar 

 disintegrating, germicidal function noted in the perito- 

 neum of the immune animal from which the serum 

 may have originated ; incapable of bactericidal ac- 

 tivity outside the body, but the influence of which in 

 the peritoneum of a susceptible animal is to call forth 

 at once this interesting phenomenon. Manifestly the 

 germicidal substance in this case is neither contained 



1 Pfeiffer : Zeit, f. Hyg. u. InfektioQskrankheiten, Bd. xviii. p. 1 ; Ebenda, 

 Bd. XX. p. 198. 



