430 INFECTION AND IMMUNITY. 



which in themselves are non-toxic; they become 

 me nt. toxic only through the aid of complements which 

 are present in the body of the poisoned animal. 

 In this instance, complement which usually is a 

 source of protection becomes a source of danger to 

 the animal possessing it. Not only does ordinary 

 serum-complement serve for activation, but Kyea 

 discovered that cells (erythrocytes) may contain 

 another kind of complement, an "endocomple- 

 ment," which activates the amboceptors after the 

 latter have combined with the cells. Flexner and 

 Noguchi found that this also was the case with 

 the neurotoxic amboceptors. 



The ability of lecithin to activate the hemolytic 

 amboceptors of cobra venom and the preparation 

 of cobra-lecithid (Kyes) were described in Part II, 

 Chapter XVI. In the preparation of cobra-leci- 

 thid the neurotoxin is separated from the hemo- 

 lysin, the former remaining in solution, whereas 

 the latter settles as a precipitate in combination 

 with the lecithin. Immunization with the neuro- 

 toxin isolated in this way causes the formation 

 of a specific antineurotoxin (Elliot). The neuro- 

 toxin may also be abstracted from the venom by 

 treating the latter with the nervous tissue of a 

 susceptible animal (Flexner and Noguchi). 



The hemotysin is distinct from the hemagglu- 

 tinin and the latter may be eliminated by heating 

 the venom to from 75 to 80 C. In the action of 

 venom on erythrocytes agglutination precedes he- 

 molysis. 



and The toxins may be converted into toxoids by 

 heat or treatment with chemicals. Immunization 

 with toxoids causes the formation of antitoxins. 



