304 



COLLECTED STUDIES IX IMMUNITY. 

 TABLE VII. 



* Only slight solution. 



These contradictory results are not to be harmonized with Cal- 

 mette's conception of a definite antibody which is destroyed at 56 C. 

 One would have to assume that this normal antihaemolysin were 

 lacking in horse serum, for as a rule this does not become more strongly 

 hsemolytic by heating to 56 C. On the other hand in the case of a 

 serum like No. II, which has no activating properties even when 

 heated to 56 C., it would be necessary to believe that the activator 

 is entirely absent. The conditions are still more complicated by 

 the fact that one and the same serum can behave differently toward 

 various species of blood. Thus a horse semm heated to 100 will 

 activate cobra venom for ox blood in high dilutions (0.02 complete), 

 whereas even in large amounts it dissolves goat blood only in com- 

 paratively slight degree (0.35 cc. moderate solution). In this case, 

 then, the activator present is in the main one for ox blood, not for 

 goat blood. 



Believing that an insight into the nature of this maze of facts 

 could be gained only by a thorough chemical analysis, we sought to 

 isolate the thermostable activating substance. First we succeeded 

 in proving that when serum is precipitated with 8 to 10 volumes of 

 alcohol, the activating substance passes into the alcohol, while the 

 inhibiting substance is contained in the precipitate. For if the 



