526 Chapter XVI 



micro-organisms, nor between nutritive substances and living micro- 

 organisms" (p. 225). "From Nuttall's results it must evidently be 

 accepted as possible that the phagocytes can ingest dead bacteria 

 only and that they have not the power of ridding the body of the 

 living infective agents " (p. 226). The following passage is especially 

 significant. "When we examine, with an open mind, a series of 

 preparations which show the relations between the phagocytes and 

 the bacteria in various infective diseases, the phagocytes sometimes 

 present themselves as the victims of the bacteria, which continue 

 their triumphal march ; sometimes they produce the impression of 

 tombstones lying in large numbers behind the line of battle and after 

 the end of the struggle. On the other hand, they in no way force 

 themselves upon our notice as instruments of slaughter which the 

 attacked organism makes use of to defend itself^' (p. 227). 



These arguments have been regarded by many investigators in all 

 countries as perfectly sufficient to overthrow the phagocytic theory. 

 The bactericidal power of the body fluids became the rallying cry 

 of a great number of works always directed to the same object : 

 to replace the role of phagocytosis by that of a bactericidal power 

 of the body fluids. It is quite unnecessary to weary the reader with 

 a list of the very numerous publications that have appeared on this 

 subject in every European language. But it is not possible to pass 

 over in silence the work of some of the principal partisans of the 

 humoral theory of immunity. 



The first place amongst these works certainly belongs to von 

 Behring's memoir^ on the natural immunity of white rats against 

 anthrax. As already stated in Chapter vi of this work, von Behring 

 discovered the very remarkable power possessed by the rat's blood 

 [550] of destroying anthrax bacilli with very great rapidity. This inves- 

 tigator did not hesitate to conclude therefrom that this bactericidal 

 property of the blood must, in the rat, bring about a great resistance 

 against anthrax. We should have in this case, then, an example in 

 which the immunity did not depend in any way upon phagocytosis, 

 but would be bound up entirely in a purely humoral property. 



With the object of deciding whether the bactericidal property of 

 the blood is really the general and essential cause of natural or 

 acquired immunity, von Behring, in collaboration with Nissen^, carried 

 out a long series of experiments, the results of which, however, did 



1 Centralbl.f. klin. Med., Bonn, 1888, No. 38. 



2 Ztschr.f. ^y^., Leipzig, 1890, Bd. viii, S. 412. 



