THE PROTECTIVE SUBSTANCES OF THE BLOOD. 387 



ceptors. The haemolysins occurring naturally and those artificially 

 produced manifest their action according to exactly the same mechan- 

 ism. According to the observations of Pfeiffer and of Moxter, as 

 well as to certain experiments of Wechsberg and M. Neisser, still 

 to be published, the same holds true for the bactericidal substances. 



Against this view Buchner, while in general he confirms our find- 

 ings of fact, maintains that the thermostable substances of normal 

 sera are not analogous to the immune bodies, but are something 

 apart by themselves. He therefore gives them a distinct name, 

 " Hilfskorper " [= aiding body]. Such a separation of the con- 

 nection between the physiological and the pathological is opposed 

 to the teachings of Virchow. Aside from this, however, I regard 

 the proof which Buchner advances for placing these " Hilfskorper " 

 by themselves as insufficient. It is entirely negative and consists 

 in this, that, according to Buchner, proof has not been offered that 

 in normal haemolysis "a " Hilfskorper " does not always come into 

 action. Against this I should like to point out that, in the very 

 large number of cases of normal haemolysis studied during the past 

 years by myself and fellow workers, we have always succeeded in 

 discovering the amboceptor effecting the action. At times, of course, 

 this required a great deal of labor and trying all sorts of sources 

 for complement. Experiments like those recently published by 

 Buchner, in which only one combination chosen at random from 

 the many possible ones is employed, do not argue against the pres- 

 ence of amboceptors in case the experiment results negatively, for 

 no one versed in this subject would assume that every amboceptor 

 must find a fitting complement in every serum used. Hence Buchner 

 does not furnish any proof that hamolysis can be produced by the 

 alexin alone. 



In connection with this I should like to call attention to the fact 

 that the alexin or complement action possessed by normal serum is 

 due to a plurality of substances, not to a single one. Each comple- 

 ment by itself is harmless, for only through the intervention of the 

 amboceptor is its injurious action carried over to certain tissues. 

 When this occurs, however, the action is the same on its own as on 

 foreign tissues. It is surprising to watch how guinea-pig blood-cells 

 which have been loaded or sensitized with certain amboceptors at 

 once dissolve if their own serum is added, this serum now acting as 

 a deadly poison. There is very little ground, therefore, to regard the 

 complements as playing the role of defenders against foreign invaders. 



