184 MICROBES AND TOXINS 



occurs when the venom is added. But if now to this mixture 

 of carefully washed goats' corpuscles and venom a little normal 

 blood serum is added, haemolysis proceeds at once. It would 

 seem from these facts that the venom acts like a sensibilisatrice 

 or immune-body, the normal serum providing the alexine or 

 complement. 



But there are other facts which forbid this interpretation. 

 Normal serum activates the venom, it is true, but even when 

 heated to 65 C. or higher it still activates : there exist even 

 normal sera which cannot activate venom haemolysis until they 

 have been heated at 100 C. It is inconceivable that it is the 

 complement which is the active agent since complement is 

 destroyed at 56 C. 



Further, washed corpuscles of certain animals are laked by 

 the venom without any addition of fresh serum (corpuscles of 

 dog, rat, guinea-pig, and man). Again, in the case of the 

 washed goats' corpuscles, normal serum is not the only 

 substance which can activate : laked red corpuscles, e.g., of the 

 guinea-pig, can take its place quite well. Finally, in this last 

 example it is not the fluid which acts, but the stromata or 

 bodies of the corpuscles which have shed their haemoglobin, 

 and these still possess their activity after heating to 100 C. 

 It is thus impossible to attribute the activating action to the 

 complement or even to the serum as a fluid. The active 

 substance is not the complement nor is it an albumin, for 

 albumin coagulates below 100 C. It is not a ferment, for a 

 ferment heated in solution above 100 C. is no longer active. 

 It is a definite chemical substance present in the serum and 

 in the stroma of the blood corpuscles, namely lecithin. 

 Lecithin is a well-defined chemical body, unlike albumin, for 

 which we are unable to write a formula, still more unlike the 

 complement and the immune body which, like the ferments, are 

 known as activities or properties, not as substances. In venom 

 haemolysis, therefore, our knowledge is more complete and 

 clear than in the haemolysis of haemolytic sera. 



Lecithids. When blood of any species is easily laked 

 by venom without addition of serum (e.g., in man, the rat, 



