THE ISOLATIONS 7 OF SNAKE VENOM LEC1THIDS. 471 



19 cc., is then mixed with five times its volume of chemically pure 

 ether which has been distilled over sodium. A precipitate forms 

 consisting of the desired cobra venom lecithid, while the lecithin 

 remains dissolved in the ether. 



Precipitate and fluid are separated by means of the centrifuge, 

 the original volume of ether again added, shaken, and the mixture 

 once more centrifuged. This is repeated at least ten to twenty times 

 in order to remove any adherent lecithin. The substance thus ob- 

 tained is the cobra venom lecithid. 



The product can be kept for a long time under ether, apparently 

 undergoing little or no change; or it can be carefully dried, through 

 which, however, it suffers some change, affecting especially its solu- 

 bility but not its action. The yield of dry substance is quite large, 

 1 grm. of dry cobra venom yielding about 5 grms. dry lecithid. 1 



After having worked out the best method for obtaining the cobra 

 lecithid it was next necessary to determine by biological means 

 whether the product isolated by us showed itself through its specific 

 action to be the co bra-am boceptor-lecithin combination sought for. 

 That this was actually the case could be proven in two ways, 

 namely : 



1. By showing that the extracted watery fluid has lost its hsemo- 

 lytic property, and 



2. By showing that this property is now present in the chloroform- 

 lecithin solutions (see Table 1). 



So far -as the behavior of the aqueous solution is concerned it can 

 actually be shown that the single treatment with chloroform-lecithin 

 removes all but traces of the haemolytic power, and that a repetition 

 of the procedure suffices to remove all of the hsemolytic agent from 

 the watery solution Corresponding to this we find that the haemo- 

 lytic power of the watery solution has been transferred completely 

 to the chloroform-lecithin portion, a fact which shows that the leci- 

 thin has united with the cobra venom (Table I). 



1 If one has but very little of the primary substance at one's disposal another 

 method of preparing the lecithid can be tried, one which will answer at least 

 for preliminary examinations. 1 cc. of a 4% -aqueous solution of cobra venom 

 is mixed with 1 cc. of a 20% solution of lecithin in methyl alcohol, the mixture 

 is kept in an incubator for several hours and frequently shaken; then 10 cc. 

 absolute ethyl alcohol are added and the precipitated albuminoids separated 

 by filtration. On precipitating the clear filtrate with ether, one obtains the 

 lecithid. 



