THE ISOLATION OF SNAKE VENOM LECITHIDS. 475 



In its properties the insoluble portion corresponds entirely with the 

 secondary lecithid precipitate from aqueous solutions. To obtain 

 the secondary lecithid as a pure product, however, the method first 

 mentioned seems preferable, namely, that which starts with the aque- 

 ous solution of the primary substance; the result seems to be a lighter- 

 colored product. 



It is natural that this lecithid when finished differs in its action 

 in many ways from the cobra amboceptor. It can readily be under- 

 stood that the cobra lecithid acts on the blood-cells of all the species 

 thus far examined, no matter whether these cells possess available 

 lecithin or not. One fact of considerable interest has been discov- 

 ered, namely, that the absolute quantity of lecithid necessary for 

 hfemolysis is the same for the blood-cells of different species. We 

 found that an amount of lecithid which corresponded to about 0.003 

 mg. dry cobra venom was able to dissolve 1 cc. of a 5% suspension 

 of blood-cells of different species (guinea-pig, rabbit, man, ox). This 

 quantity, we may add, corresponds to the amount of cobra venom 

 which causes solution of the blood-cells in the ordinary test when a 

 large excess of lecithin is present. 



An observation which is also of considerable interest is a com- 

 parison of the time necessary for the action of the cobra lecithid and 

 the amboceptor, with and without the addition of lecithin. In our 

 previous papers we pointed out that when cobra venom is allowed 

 to act on susceptible blood-cells, solution occurs after a considerable 

 period of incubation, so that in case a minimal quantity is employed 

 12 to 18 hours (two hours at 37, then at 8) elapse before complete 

 solution is effected. Even if a suitable excess of cobra venom and 

 the most susceptible species of blood are employed, at least 10 to 

 30 minutes will usually elapse before solution is completed. Similar 

 differences are observed if, as previously described, we allow cobra 

 venom and lecithin to act on unsusceptible blood-cells. In 

 that case, again, with minimal quantities of lecithin and ambo- 

 ceptor 6 to 18 hours are necessary to effect solution; this time 

 is decreased if large excesses are employed, but solution is never 

 instantaneous. 



In contrast to this a marked decrease in the period of incubation 

 is observed if the finished lecithid is used, solution being instantaneous 

 on the employment of cencentrated solutions. The shortening in 

 the time necessary for solution becomes particularly marked when 

 small doses of the lecithid are used, solution commencing at once 



