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COLLECTED STUDIES IX IMMUNITY. 



In view of the exceeding importance of these questions it seemed 

 advisable to proceed from these new facts and attempt to penetrate 

 more deeply into the mechanism of the snake venom's action. We 

 had at our disposal two specimens of dried cobra poison the hasmolytic 

 strength of which had proved to be almost identical and for which 

 we are indebted to Dr. Lamb and Prof. Calmette. 



A one per cent solution of the dried cobra poison in 0.85% salt 

 solution served as our standard poison. This solution when kept 

 on ice was preserved unchanged for several days. 



The experiments were made with the following animal species: 

 man, ox ; horse, goat, sheep, dog, rabbit and guinea-pig. Guided 

 by Flexner and Noguchi's observations, we at first used only blood- 

 cells which had been freed from serum. This was accomplished 

 by making a 2% suspension of the cells in 0.85% salt solution, 

 centrifuging, decanting the fluid, and then adding anew the same 

 amount of salt solution. This was always done twice and then a 

 5% suspension was made. 



All the tubes of a given series contained 1 cc. of a 5% blood 

 suspension and they were all made up to the same volume (2 to 

 2.5 cc.) by the addition of salt solution. The specimens were kept 

 in the incubator at 37 C. for two hours, and then placed on ice at 

 6 to 8 C. until the following morning. 



According to our experience there are two kinds of blood-cells 

 so far as their behavior toward cobra venom is concerned : 



(1) Those that in themselves are dissolved by the cobra venom. 



(2) Those that are affected by the cobra venom only after the 



addition of other substances (complements, etc.). 

 The following table will show the behavior of washed red blood- 

 cells of various species toward cobra venom: 



TABLE I. 



