REACTIONS BETWEEN ANTIBODIES 35 



0.25 c.c. of normal hydrochloric acid, which caused the 

 binding between the toxin and antitoxin to be dissolved. 

 This was proved by the acid mixture being heated to 

 iooC. for thirty minutes, whereby the antitoxin was de- 

 stroyed, whereas the poison itself was not sensibly weak- 

 ened. This could be shown by neutralising the solution 

 after it had cooled down to the room's temperature. The 

 toxicity of the solution was nearly the same as that of 

 the original solution without antitoxin. In this case the 

 peculiarity occurs, as Sachs has first shown, that the pres- 

 ence of acid protects the poison from being destroyed by 

 heat. 



Morgenroth criticises a theory sketched by Nernst 1 and 

 developed by Biltz, Much, and Siebert, 2 according to which 

 the toxins are "adsorbed "to the "colloidal" anti-toxins 

 and thereafter destroyed. Morgenroth says rightly that 

 this theory, "which as yet is void of any experimental 

 basis," is completely disproved by his experiments. 



As will be shown later on, the velocity of reaction of 

 the different toxins changes with temperature according to 

 a law which was deduced from therm odynamical considera- 

 tions, involving the validity of van't Hoff's law for solu- 

 tions. The applicability of this law to the velocities of 

 reaction of toxins may therefore be regarded as a new 

 proof that the general laws bearing on the behaviour of 

 common matter are valid even for the processes going on 

 between the substances studied in the phenomenon of 

 immunity. No single proof has been adduced against the 



1 Nernst : Zeitschr.f. Elektrochemie, B. 10, No. 22 (1904). 



2 Biltz, Much, and Siebert : Behrings Beitrage (1905). 



