114 CHEMICAL EQUILIBRIA 



bacillus. This poison has the not uncommon pro- 

 perty of killing the red blood-corpuscles in such a 

 way that the haemoglobin leaves them and enters 

 into the surrounding solution. The experiments 

 are made in test-tubes, containing red blood -cor- 

 puscles, to which the mixtures of lysin and antilysin 

 are added in given quantities (the total volume being 

 iocc. filled up with 0-9 per cent NaCl solution), 

 and the blood is haemolyzed in the higher degree 

 the more free toxin is present. Now every test-tube 

 contains hundreds of thousands of red blood-cor- 

 puscles, so that every observation gives a statistical 

 mean value for so many individuals, of which 

 specimens with very different sensibilities in regard 

 to the lysin occur (see p. 76 above). With guinea- 

 pigs each figure is the mean of only some ten 

 observations on as many individual animals — the 

 method commonly used is content with only one or 

 two observations for each figure. Therefore the 

 haemolytic experiments give in general much better 

 values than experiments with living animals. Con- 

 sequently the agreement with calculation is in the 

 case of haemolysins better, therefore they play an 

 important role in the doctrine of immunity. When 

 I worked in Dr. Madsen's institute I observed the 

 very pronounced similarity between the partial 

 neutralization of a weak acid by a weak basis, and 

 the neutralization of tetanolysin by its antilysin 

 according to Madsen's experiments (represented in 

 Fig. 30, middle curve) made in Ehrlich's institute. 

 Now the bases are lysins ; I therefore proposed that 



