404 COLLECTED STUDIES IN IMMUNITY. 



Resume. 



1. The property of certain sera to activate cobra venom, a prop- 

 erty which is lost by heating the sera to 56 C., depends on the presence 

 of complements in the restricted sense. 



2. The activating property of blood solutions depends on the 

 lecithin contained in the red blood-cells; this also gives rise to the 

 susceptibility of the blood-cells against cobra venom alone. The 

 lecithin which comes into play is a constituent of the stromata. 



3. The fact that blood solutions are inactivated by heating to 

 62 C. is due to the combination at this temperature of the lecithin 

 with the haemoglobin; suspensions of blood stromata are not inacti- 

 vated at this temperature. 



4. Cholesterin inhibits to a high degree haemolysis by means of 

 cobra venom alone, and of cobra-venom-lecithin. When serum 

 complements are used for activation, cholesterin exerts little or no 

 protective action. 



5. Cholesterin does not inhibit haemolysis due to staphylolysin 

 and arachnolysin, but very markedly inhibits that due to teta- 

 nolysin and to olive-oil. 



6. The quantitative relations between cobra venom and lecithin 

 correspond to those of amboceptor and complement; the more cobra 

 venom present the less lecithin will be required for haemolysis, and 

 vice versa. A deflection of lecithin does not occur unless very large 

 amounts of cobra venom are used. 



7. Most species of blood are susceptible even to cobra venom 

 alone. The "absolute susceptibility" determined with the optimum 

 addition of lecithin may be many times that obtained without the 

 addition of lecithin. 



8. Hydrochloric acid exerts a marked protection on cobra venom 

 against destruction through high temperatures. Potassium per- 

 manganate, chloride of lime, chloride of gold, soda lye destroy cobra 

 venom (experiment with blood + lecithin). 



9. Bile activates cobra venom ; milk (goat) only after it has pre- 

 viously been heated to 100 C. 



10. Fatty acid, soaps, chloroform, and neutral fats have a haemo- 

 lytic action. The hsemolytic action is somewhat increased on the 

 .addition of cobra venom. 



11. Lecithin and cephalin, on the other hand, exert a haemolytic 



