THE MODE OF ACTION OF COBRA VENOM. 311 



between the activating power of fresh and of heated serum. In 

 this case evidently the fresh serum already contains free, i.e. active, 

 lecithin, and the inhibiting substance is affected but to a slight 

 degree by the heating. In view of all this it is certainly incorrect 

 to speak, as Calmette l does, of a definite thermolabile antibody 

 which is destroyed at 56 C. 



It is natural to attempt a quantitative estimation of the cobra 

 amboceptor by means of the binding of lecithin; also to think of 

 the possibility of isolating the cobra amboceptors as lecithids. Ex- 

 periments in this direction are now under way. 



The results of the. experiments here given furnish a further in- 

 sight into the nature and mode of action of the amboceptors. The 

 demonstration of cndocomplemcnts, as well as the significant fact that 

 a definite chemical and crystalline substance, lecithin, can in a certain 

 sense play the role of complement, would appear to be especially im- 

 portant for the development of our knowledge concerning poisons. 



1 One might assume that the haemolysis by cobra venom alone, ascribed in 

 II to the action of the endocomplements, was caused by the lecithin contained 

 in the red blood-cells. This assumption, however, is at once excluded by the 

 fact that the endocomplement solutions are inactivated by heating to 62 C., 

 showing that their action has nothing to do with that of the lecithin. 



