SUBSTANCES WHICH ACTIVATE COBRA VENOM. 449 



substance is absorbed by yeast. In the same connection we may 

 perhaps mention that when fresh guinea-pig serum is shaken with 

 ether it loses not only the other complementing functions but also 

 that for cobra poison. If guinea-pig serum which has been heated 

 to 100 C. (and which therefore owes its activating property to the 

 lecithin liberated through heat) is treated with ether in exactly the 

 same manner, the complementing function remains unchanged. 



II. The Lecithin Content of the Stromata and the Activation of Cobra 



Venom Dependent Thereon. 



In the investigation of the substances in the red blood-cell termed 

 endocomplements we were at first led into error by the employ- 

 ment of just this method of differentiation dependent on the de- 

 structibility of complements by means of ether. 



For these experiments we used the combination ox blood + cobra 

 venom + solution of guinea-pig blood. The latter was obtained by 

 dissolving sedimented guinea-pig blood in distilled water. The solu- 

 tion was made up to three times the original volume of blood, where- 

 upon NaCl was added until the solution contained 0.85^. If such 

 a solution is shaken with highly purified ether (1 volume blood 

 solution + 10 volumes ether) and a sample of the solution (separated 

 bv means of a separating-funnel) is tested it will be found that this 

 has lost its power to activate cobra venom. The ethereal residue 

 taken up in salt solution also exhibited no complementing properties, 

 so that it appeared as though the substance termed "endocomple- 

 ment " was destroyed by the ether just as were the serum comple- 

 ments. This, however, is not the case. When the blood solution 

 separates after shaking with ether an emulsified stratum is formed 

 between ether and blood solution. On testing that part of the blood 

 solution which contains this intermediary stratum the entire quantity 

 of the activating substance is recovered. (See Table VI.) 



This shows, therefore, that the activating substance had not been de- 

 stroyed, but that it had escaped our observation, owing to the peculiar 

 behavior of the emulsified stratum. It is well known that such emul- 

 sions take up minute solid particles most readily, and it was natural 

 therefore to assume that the activator contained in the blood-cells 

 is connected with their stromata. In laky blood solutions the stro- 

 mata are present in a swollen state; hence we sought to separate 

 the stromata from the rest of the haemoglobin solution. With guinea- 



