TUBERCULIN AND MALLEIN 183 



poisons, and since haemolysis is a phenomenon much more 

 convenient to follow experimentally than paralyses or nervous 

 symptoms, they have been much studied, and from certain 

 points of view are better known than the microbial toxins. 

 The study of the toxins has profited by that of the venoms. 

 Thanks to some beautiful experimental results, there is reason 

 to believe that, with the help of the venoms, the study of 

 toxins in general may make the advance so much desired by 

 science, and from a physiological subject, studied only in the 

 living animal, become a part of chemistry with its definite 

 reactions. 



Some definitions and examples must first be given. 



When a rabbit is repeatedly inoculated with, for example, 

 defibrinated sheep's blood, the rabbit's serum acquires the 

 property of dissolving the red corpuscles of the sheep : these 

 latter suspended in physiological saline solution in a test-tube 

 with a little of this rabbit's serum, instead of settling intact 

 and leaving a colourless supernatant fluid, break up, liberate 

 their haemoglobin, and colour the fluid red. The rabbit's 

 serum has become haemolytic for the red corpuscles of the 

 sheep. 



Bordet has shown that haemolysis depends on the operation 

 of two substances, or rather of two functions, of which we 

 shall have much to say in connection with immunity : one is 

 the alexine or complement of normal serum (destroyed by 

 heating to 56 C. for one hour) ; the other is the sensibilisatrice 

 or immune-body of the serum of immunised animals, such 

 as the rabbit above mentioned (it stands heating to 68 or 



70 c.). 



The latter owes its name to the fact that it prepares or 

 renders sensitive the red corpuscles towards the action of the 

 complement. The complement completes the action of the 

 "sensibilisatrice," hence its name. If we take the blood 

 corpuscles of a goat and add a little cobra-venom, haemolysis 

 occurs. But if the blood corpuscles are first carefully washed 

 with physiological saline so as to be entirely freed from traces 

 of blood serum which might adhere to them, no haemolysis 



