476 



COLLECTED STUDIES IN IMMUNITY. 



and being completed within 15 to 20 minutes. In other words, the 

 increase in the rapidity of the process is about twenty-fold. 



This behavior is significant, for it shows that in this case the period 

 of incubation is due not to a slow action of the anchored toxophore 

 group (lecithin), but exclusively to the slow development of the real 

 toxic agent, the lecithid. The difference in the time of action in the 

 case of small and large doses is in accordance with the well-known 

 law that the reaction (in this case the union of cobra amboceptor 

 and lecithin) proceeds more rapidly in concentrated solutions than 

 in weak ones. 



TABLE III. 



'The solution ol cholesterin was made by diluting 1 cc. of a saturated solution of Cholesterin 

 in hot methyl alcohol, with 9 cc. 85% salt solution 



A third difference between cobra amboceptor and the finished 

 lecithid is seen in the behavior toward high temperature. The aqueous 

 solution both of the primary and the secondary cobra lecithid is 

 far more stable than solutions of the amboceptor alone. The former 

 can be heated to 100 C. for six hours without any particular loss in 

 power, while the amboceptor of cobra venom loses its action if heated 

 to 100 C. for only thirty minutes. Obviously this is to be explained 



