THE MODE OF ACTION OF COBRA VENOM. 



303 



TABLE VI. 

 1 cc. 5% HORSE BLOOD 4- Ox SERUM. 



It seemed to us that it was of the highest importance to gain 

 a further insight into these thermostable activating substances. To 

 begin, we found that the substance is far more stable than Calmette 

 assumed, for activation is effected even by sera which have been 

 cooked for hours. Thereupon we investigated a number of sera in 

 respect to their activating power and obtained results that were 

 little less than confusing. We found sera which activated not only 

 in the fresh state but also after heating to 56 C. and 100 C. (No. I 

 of Table VII). Other sera did not activate either when fresh or 

 after heating to 56 C. ; they did activate, however, when they were 

 heated to 65 and 100 C. (No. II of Table VII). As a rule in these 

 cases the serum heated to 100 C. proved more powerful than that 

 heated to 65 C. A third class of sera was found which did not activate 

 when fresh, but activated when heated to 56 C. or higher (No. Ill of 

 Table VII). Finally, there is the type already mentioned, namely, a 

 serum which activates when fresh, is made inactive by heating to 

 56 C. and again made active by heating to 65 (No: IV of Table VII). 

 We have also observed sera which activate only when fresh and do not 

 again acquire this property when heated to a greater or less degree 

 (No. V of Table VIII). We see therefore that we are dealing with 

 five different combinations, 1 as is shown in Table VII. 



1 Naturally in the case of such bloods as rabbit blood, which are dissolved 

 by cobra poison alone, only such amounts of poison have been used which by 

 themselves are not active, but which cause haemolysis when they are combined 

 with suitable reinforcing agents (complements, etc.). 



