558 BAGTERIOLOOY. 



mal protective (Buchner's alexins) having no specific 

 relations to any particular variety of infection, but oifer- 

 ing some protection, more or less complete, to the ani- 

 mal against all bacterial invasion. By the methods 

 employed in the preceding experiments it seems likely, 

 in the light of more recent work, that this normal anti- 

 dote was simply temporarily accentuated through the 

 tissue-stimulation resultant upon the treatment that the 

 animals had received, for it is not possible to bring 

 about in this way as high or as permanent a degree of 

 immunity in an animal from a particular disease as that 

 which can be obtained by the use of the specific micro- 

 organism causing the disease, or the products of its 

 growth, especially the latter. 



A striking illustration of this protective reaction on 

 the part of the animal tissues is brought out in the 

 course of R. Pfeiifer's ^ experiments on Asiatic cholera. 

 He found that it was possible to confer immunity upon 

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

 animals protected suscejrtible 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 instanta- 

 neous disintegrating (bacteriolytic), 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 in 

 the test-tube ; but when virulent cholera spirilla were 

 injected into the peritoneum of an animal that was not 

 immune, and this was at once followed by an intra- 

 peritoneal injection of serum from an immune animal, 



1 Pfeiffer : Zeitsclirift fiir Hygiene und Infektionskrankheiten, Bd. 

 xviii. S. 1 : Bd. xx. S. 198. 



