178 



LECTURES ON IMMUNITY 



and tetanolysin, which, on neutralisation, as we shall soon 

 see, behave in a manner very similar to ammonia. 



The following figures, found for the toxicity of tetanolysin 

 after the addition of different quantities of antitoxin, may 

 serve as an example. It is illustrated by Fig. 3. This 

 curve has a tangent at its beginning, which cuts the ^r-axis 

 in the point x =0.276, indicating that if the neutralisation 

 proceeded according to the same laws as hold for the neu- 

 tralisation of strong acids by strong bases, i.e. if the quan- 

 tity neutralised was proportional to the antitoxin added 

 until total neutralisation was reached, then 0.276 parts 

 (c.c.) of the unit of antitoxin used would neutralise com- 

 pletely the quantity of toxin used (2 c.c. of a 2 per cent 

 solution). In other words, these quantities are equivalent. 

 By the aid of this value the quantities (n) of antitoxins are 

 calculated in the following table in equivalents ( x ) of the 

 toxin present taken as unit : 



TOXICITY (?) OF TETANOLYSIN AFTER ADDITION OF n c.c. OF ANTILYSIN 



