TUBERCULIN AND MALLEIN 185 



and the guinea-pig) it means that the lecithin of the corpuscles 

 readily detaches itself and unites with the venom. When the 

 blood is laked only when serum is furnished in addition, it 

 means that the lecithin of the globules themselves is firmly 

 bound and difficult to set free. In certain cases heating to 

 65 C. or even higher is necessary to liberate lecithin from its 

 combination with haemoglobin. The experiments of this 

 kind have many complications of detail, since the three factors 

 coming into play the blood corpuscles, the lecithin, and the 

 venom are subject to many variations. A step in advance 

 has been made in what may be called the mechanical or 

 purely chemical explanation of haemolysis by the discovery 

 that lecithin forms with venom a combination of a chemical 

 character in which neither lecithin nor venom can be 

 recognized. Kyes has named this combination or " couple " 

 lecithid) or since his experiments were on cobra-venom, cobra- 

 lecithid. 



In its physical properties (solubility in water, alcohol, ether, 

 chloroform, and acetone) the lecithid differs from lecithin as 

 much as from venom. It can be isolated in a crystalline form 

 and redissolved in water. It acts on the blood of all animal 

 species, and that without any incubation period. The delay 

 observed in the action of venoms is not a period of incubation, 

 but merely represents the time necessary for the formation of 

 the lecithid compound. If the ready-made lecithin is added 

 to the blood the haemolysis is more rapid than on the addition 

 of the two elements separately. 



Strictly speaking, however, the venoms do not act without 

 incubation : the time taken by lecithid formation represents 

 the minimum incubation period. It is quite possible that in 

 the action of microbial toxins there may occur a slow forma- 

 tion (i.e., with a longer incubation period) of compounds 

 analogous to lecithids. 



Cholesterin behaves as an antagonist to lecithin ; it has no 

 effect on complement, but prevents the combined action of 

 the lecithid by affecting the lecithin ; it thus forms a sort of 

 antihczmolysin or antitoxin the composition of which is definitely 



