542 Chapter XVI 



demonstration : (1) that the phagocytes, in cases of immunity, ingest 

 and destroy the living and virulent micro-organisms without the 

 latter needing to be previously deprived of their toxins ; (2) tliat the 

 phagocytes absorb toxic substances ; (3) that the phagocytes contain 

 bactericidal cytases and produce fixatives ; the humoral theories, 

 in spite of all the efforts made to defend them, coiUd never be 

 developed as theories that were in the slightest degree of general 

 application. Certain observers who from the first were very sympa- 

 thetic to the humoral theories have attempted to give a complete 

 summary of these properties. Thus, Stern^ and later Frank^ have 

 published reports drawn up with great care and in a very impartial 

 spirit on the works treating of the properties of the body fluids 

 [566] and the part they play in immunity. This is how they sum up the 

 question. Stern came to the conclusion that it is impossible "to 

 demonstrate at all regularly the existence of relations between the 

 bactericidal action of the blood and immunity in all the infective 

 diseases. In some cases, however, these relations are so marked 

 that, for these examples, a causal bond between the two factors 

 is extremely probable." Frank expresses himself in the following 

 manner : " It follows most clearly that the immunity of an animal — 

 immunity innate or acquired — corresponds wdth the bactericidal 

 property of the blood in certain exceptional cases only. The only 

 animal, absolutely susceptible to anthrax and whose blood is entirely 

 without any bactericidal power, that it is at present possible to 

 cite, is the mouse." "The bactericidal action of the blood serum 

 is undoubtedly a fact of great biological importance ; but equally 

 certainly it cannot be the general cause of immunity, whether innate 

 or acquired." 



An attempt was made to give fresh life to the humoral theory, 

 either by assuming that the bactericidal substance is nothing but 

 the eosinophile or pseudo-eosinophile secretion of the leucocytes 

 (Kanthack), or by supposing that for the destruction of micro- 

 organisms in the animal body the intervention of the agglutinative 

 substance dissolved and distributed in the body fluids is essential 

 (Max Gruber). These two views were put forward in a tentative 

 form and as preliminary communications only ; there is no possibility 



1 Gentralbl.f. allg. Path. u. path. Anat., Jena, 1894, Bd. v, S. 212. 

 ^ Lubarsch u. Ostertag's " Ergebnisse d. allg. Path. u. path. Anat," Wiesbaden, 

 1895, I. Abt, S. 384. 



