THE MECHANISM OF THE ACTION OF AMBOCEPTORS. 217 



of diphtheria poison in the animal body, at first a loose one, soon 

 becomes more and more firm so that it cannot be broken up even 

 by very large amounts of antitoxin. Madsen's l experiments, to 

 liberate, by means of antitoxin, tetanolysin which had been anchored 

 by the blood-cells, also confirm this. 



Blocking by means of complementoids is also of value for the 

 technique of demonstrating the presence of amboceptor. Suppose, 

 for example, that in doubtful cases one seeks to show the existence 

 of the amboceptors in the usual manner, by sensitizing the red blood- 

 cells and subsequently complementing with a different kind of serum. 

 In this case, owing to the blocking action of the complementoids, 

 an absence of the amboceptors could be simulated. In this connec- 

 tion it is of considerable interest to know that so capable an investi- 

 gator as Buchner 2 employed the above method for analyzing the 

 hsemolysin in just the case here described. His attempts to demon- 

 strate the amboceptor by this method (inapplicable in this particular 

 instance) , as well as by means of the amboceptor's thermolability a 

 (already discussed), were unsuccessful. 



II. Amboceptor or Sensitizef ? 



In another case we have met with a different complication 

 equally fatal to the successful demonstration of the amboceptor by 

 routine procedures. This is of especial interest for the theory of 

 haemolysin action, and concerns the hsemolytic property of ox serum 

 for guinea-pig blood. If the ox serum is inactivated, this property 

 can readily be restored by the addition of active horse serum. If, 

 however, one tries by means of active horse serum to complement 

 blood-cell sediments (obtained by centrifuging guinea-pig blood after 



1 Madsen, Uber Heilversuche im Reagensglas. Zeitschr. f . Hygiene, Vol. 32^ 

 1899. 



2 H. Buchner, Sind die Alexine einfache oder complexe Korper? Berl. 

 klin. Wochenschr. 1891, No. 33. 



3 According to the newer researches already mentioned it would be con- 

 ceivable that the thermolability of the amboceptors is simulated by this, 

 that the complementoids, in themselves possessing a relatively high affinity, 

 become firmly anchored to the amboceptors. However, as special experiments 

 have shown us, such is not the case, for dog serum which has been inactivated 

 by shaking with yeast, and which therefore contains no complementoid, likewise 

 loses its ability to be activated when it is heated to 60 C. It does not lose 

 this power when heated only to 50-51 C. 



