NEUTRALISATION OF H^MOLYSINS 173 



that the toxicity of the first solution is half as great as that 

 of the second solution. The effect of the neutralisation of 

 the sodium hydrate by the addition of hydrochloric acid 

 may therefore be graphically represented in the following 

 figure by the line AB. The toxicity is here ordinates, and 

 the quantity of acid added is abscissae. This line would 

 be a straight line if the effect of the salt did not produce a 

 perturbing influence. 



When we have added the acid necessary to neutralise 

 the free alkali (point B\ we have still to add a small quan- 

 tity to neutralise the alkali bound in the erythrocytes, and 

 then further add a small quantity of acid before the solu- 

 tion is strong enough in acid to give haemolysis again. 

 These portions are represented by the parts BC and CD 

 in the diagram. On the addition of more acid to the solu- 



u BC D 



FIG. i. 



tion its toxicity increases nearly proportionally to the 

 quantity of free acid (neither bound to the alkali, nor in 

 the erythrocytes). This toxicity is represented by the al- 

 most straight line DE. 



In quite the same manner the toxicity changes on the 



