34 TOXINS AND ANTITOXINS. 



intoxication, it emerges from the test gifted with a 

 new property, which may be augmented by habitua- 

 tion, and which borders on immunity. 



At first we were content to vaccinate small 

 animals in the laboratory, but in proportion as the 

 discoveries in this domain extended, and there 

 developed a need for large quantities of antitoxins, 

 recourse was had to the larger animals, particularly 

 horses and cattle. From the moment that large 

 quantities of blood and antitoxic serum were at 

 command, search was made for a means of isolating 

 the antitoxin and determining its properties. 



Experiments so far made have shown that the 

 antitoxins are substances of an albuminoid nature, 

 of unknown composition, and which are very closely 

 united to the albuminoid substances of the serum. 

 It must be observed, however, that Behring and 

 Knorr oppose the assertion regarding the albuminoid 

 nature of tetanic antitoxin, but their reasons for 

 this do not appear to be well founded. 



In general, these antitoxins are precipitable with 

 the globulins, and possess quite considerable powers 

 of resistance towards physical and chemical agents. 

 Thus they are destroyed only at a temperature 

 above 60-65 C. Kept in the dry state, in the 

 residue of evaporated serum, and away from the 

 light and all oxidizing action, it is possible to pre- 

 serve their activity for a very long time. 



They are essentially humoral substances; they 



