THE COMPOUND H^MOLYSINS 235 



As will be seen from these figures, the agreement be- 

 tween experiment and calculation is very satisfactory and 

 the differences lie within the possible errors of observation. 

 For low values of x, the observed values are generally less 

 than the calculated ones, which may be due to the devia- 

 tion from the rule of square roots. The time of reaction 

 was long enough to yield nearly the limit value of the 

 reaction, so that it was not necessary to measure the time 

 with great exactitude. 



If, now, the immune-body acted like a catalytic agent, 

 we might expect that the haemolysis, at a constant concen- 

 tration of immune-body, would increase with the quantity 

 of alexin, as it indeed does if the quantity of immune-body 

 is not very low. But if the quantity of alexin is sufficient 

 for total haemolysis( > 5), then the reaction should attain 

 total haemolysis more slowly with low quantities of immune- 

 body and more rapidly with higher quantities. 



For small quantities of immune-body the limit of reaction 

 would therefore not be reached before total haemolysis was 

 attained, as soon as b > 5. This does not agree at all with 

 experience. With small quantities of immune-body the 

 haemolysis shows itself to be nearly independent of the 

 added quantity of alexin as soon as this exceeds a certain 

 quantity (b > 10). This can be explained only by assuming 

 a chemical reaction in which the immune-body contributes 

 material to the formation of haemolysin. With low quan- 

 tities of immune-body there cannot be formed a greater 

 quantity of haemolysin than is equivalent to the available 

 quantity of immune-body; the added quantity of alexin may 

 be of any magnitude. This corresponds very well with 

 the observations and the same reasoning is evidently valid 



