228 Professor Svcwte Arrhenius [June 9, 



often found pernicious, because the foreign blood " killed " the human 

 red blood-corpuscles. This noxious action is due to the serum of the 

 animal blood. Only blood from the same species is harmless. Darem- 

 berg proved, in 1891, that the "globulicid" action of the foreign 

 blood is lost if it is heated to 50^-60° C._ 



In the same manner blood-serum is " bactericid," i.e. it kills 

 bacteria (Fodor, 1887). This " bactericid " property of the serum 

 also vanishes after heating to 60° C. (Buchner). 



In 1894, Pfeiffer found that the " bactericid " action of an 

 animal's serum is increased in a very high degree if the animal 

 receives injections of a suspension of the bacteria in question. This 

 serum thereafter contains a bacteriolysin specific to the injected 

 bacilli (Pfeiffer used cholera-vibrions). Bordet then proved that 

 these hemo- and bacteriolysins are compound substances, consisting 

 of one part, alexin, which is rapidly decomposed on heating to 55° 

 (see above, YI.), and one part, the immune-body, which resists this 

 high temperature. This immune-body is specific against the injected 

 cells, and is absorbed by them in a very high degree (see above, VI.). 

 It does not alone cause lysis ; but after the addition of some alexin 

 (guinea-pig serum is mostly used as alexin), it gives a strong lysis. 

 Red blood-corpuscles, containing the immune-body, are therefore 

 rapidly hemolyzed if they are brought into a serum. 



The serum containing the immune-body acts also by agglutinat- 

 ing red blood-corpuscles, against which it is specific. It has 

 been much discussed whether this agglutinin is identical with the 

 immune-body or not, and the same question has been raised 

 regarding the bacteriolysins and accompanying agglutinins. The 

 influence of foreign substances changes the two qualities in differ- 

 ent proportions, and therefore it has been concluded that we 

 have to deal with two different substances. As we have seen above, 

 this conclusion is not very certain (see above, VIII.). 



Bordet supposed that the immune-bodies act as sensibilizators. 

 Ehrlich and his school held the opinion that a chemical compound 

 of the immune-body and the alexin is formed, which has hemolytic 

 properties. They further thought that this compound is bound to 

 the red blood-corpuscle, which they treat as if it were a l)ig molecule. 

 This latter view seems very improbable ; the fact is that the hemo- 

 lytic molecule is formed within the blood-corpuscle, where it attacks 

 some albuminous substances and causes hemolysis, just in the same 

 manner as do the simple hemolysins (e.g. tetanolysin). 



If Bordet is right, the hemolytic action would be proportional 

 to the product of the added (quantity of alexin and that of innnune- 

 body, oi- perhaps to some power of these quantities. This is really 

 the case for the action of cobra-poison in presence of lecithin (see 

 above, VI].),and therefore this case may be regarded as due to a sen- 

 sibilizing action of the lecithin. As a mattei- of fact, Ehrlich re- 

 garded this case as a typical paradigm for the binding of immune-body 



