506 



COLLECTED STUDIES IN IMMUNITY. 



ing the bouillon to stand, the toxin zone would decrease and the 

 toxon zone become considerably greater. In this case, however, we 

 see that the toxin zone remains constant while the toxon zone is 

 reduced to one-fifth. 1 



DETERMINATION OF L n DOSE. 



"Faint trace," "slight," etc., denote the degree of infiltration. 



It is difficult to say a priori what has become of the toxon which 

 has disappeared. On account of certain facts which I shall mention 

 later, 1 have assumed that we are here dealing with the formation 

 of an analogue of toxoid, namely, a substance which I term "toxo- 

 noid." I conceive this to be a toxon in which the toxophore group 

 has become modified. 







1 The entire course of the decomposition, in which from day to day we could 

 observe the toxon becoming weaker and weaker speaks against the possibility 

 (in itself very remote) that the varying composition of -the bouillon is respon- 

 sible for the variation in the number of toxons in the individual poisons. In 

 the poison here described the decomposition has taken place in the same bouillon 

 and in so short a time that very great alterations in the bouillon appear to be 

 excluded. 



