274 



INFECTION AND IMMUNITY. 



Endocom- 

 plement. 



Lecithin 

 Activation 



sary for its toxic action. The venom itself con- 

 tains only the amboceptors, hence the toxicity of 

 the substance depends on its being complemented 

 after it is introduced into the body. The posses- 

 sion of suitable complement,, therefore, is a source 

 of danger in this instance rather than a means of 

 protection for the individual. One may very well 

 suspect that a similar relationship is possible in 

 connection with other substances which are as yet 

 unknown. 



A fact of additional importance is that the am- 

 boceptor finds suitable complement not only in the 

 serum of the animal but it may also be activated 

 by a complement which the erythrocytes them- 

 selves contain. Kyes speaks of the latter as endo- 

 complement, i. e., endocellular complement. 



In attempting to discover the nature of the com- 

 plement which is present in the erythrocytes, vari- 

 ous substances existing normally in the red cells, 

 as cholesterin and lecithin, were obtained in pure 

 form and their activating power for the cobra am- 

 boceptors was tested in reagent-glass experiments. 

 From this work it was learned that lecithin, a defi- 

 nitely known chemical substance, has the activat- 

 ing power, and it was, therefore, assumed that the 

 endocomplement of erythrocytes is nothing more 

 or less than lecithin. All erythrocytes contain 

 lecithin, yet not all are equally susceptible to the 

 action of venom in the absence of serum comple- 

 ment ; that is to say, endocellular lecithin does not 

 act as complement with equal readiness in all 

 cases. In order to explain this variation it was 

 necessary to assume that the lecithin in the cells 

 of one animal may be more available as comple- 

 ment because it is bound to other cell constituents 



