THE MODE OF ACTION OF COBRA VENOM. 309 



These results can be explained only by assuming that lecithin 

 and cobra amboceptor have combined to form what may be termed 

 the "lecithin" of cobra poison, and that the affinity of the cobra 

 amboceptors cytophile group is thereby increased. According to this 

 the union with the lecithin causes the cobra poison to be more 

 rapidly anchored than the cobra amboceptor alone. The increase of 

 the cytophile groups affinity through the occupation of another 

 grbup is perfectly conceivable chemically. An analogy frequently 

 met with is the fact that the anchoring of the hsemotytic serum 

 amboceptors by the blood-cells usually causes an increase in the 

 affinity of the complementophile group. Ehrlich and Sachs l have 

 shown that the occupation of the complementophile group of serum 

 amboceptors can cause an increase of the cytophile group's affinity, 

 such as is presented in this case. 



We therefore assume that the lecithin acts as a kind of comple- 

 ment since it is anchored by certain definite groupings of the poison 

 molecule. In this way a poisonous double combination is formed 

 of which perhaps the cholin residue constitutes the toxophore group. 



There is another fact which supports the view here presented, 

 namely, that the lecithin amboceptors effect solution of the red blood- 

 cells even at C., whereas the thermolabile complements of blood 

 serum are anchored only at higher temperatures. Corresponding to the 

 views formulated by Ehrlich and Marshall 2 for the amboceptors 

 (polyceptors) of blood serum, we must therefore assume that the 

 snake venom amboceptor in addition to its cytophile group possesses 

 at least two haptophore groups, of which one as usual is able to bind 

 complements, the other to bind lecithin. Each of these combina- 

 tions by itself is dominant, i.e., sufficient to effect solution of the blood- 

 cells. It is very probable that occupation of both groups increases 

 the solvent effect. 



The following experiment furnishes additional . proof that the 

 phenomena observed cannot be regarded in the light of a sensi- 

 tization. The amount of lecithin required for complete hsemoly- 

 sis is determined in two parallel series, one on the addition of 

 small amounts of cobra venom, the other with large amounts. It is 

 found that far more lecithin is required for complete solution when 

 there is a large excess of cobra venom. (See Table XI.) 



1 See pages 209 et seq. 3 See pages 226 et seq. 



