Oil Immunity luith Special Reference to Cell Life. 



427 



nients, particularly in the case of ricin, I was able, in the first place, to 

 determine that they yielded an exact quantitative representation of the 

 course of the processes in the living body. The demonstration of this 

 fact formed the basis of a more extended application of experiments of 

 this nature. It was shown that the action of toxine and antitoxine 

 took place quantitatively as in the animal body. Further, these 

 experiments yielded a striking series of facts of importance for the 

 theoretical valuation of the reaction between toxine and antitoxine. 

 It was proved in the case of certain toxines — notably tetanus 

 toxine — that the action of antitoxines is accentuated or diminished 

 under the influence of the same factors which bring about similar 

 modifications in chemical processes — warmth accelerates, cold retards 

 the reaction, and this proceeds more rapidly in concentrated than in 

 dilute solutions. These facts, first ascertained by means of test-tube 

 experiments, have since been confirmed by Behring and Knorr for 

 tetanus within the animal body, and by Martin and Cherry in the 

 case of snake-venom.* The knowledge thus gained led easily to the 

 inference that to render toxine innocuous by means of antitoxine was 

 .a purely chemical process, in which biological processes had no share. 

 Yet again insurmountable obstacles seemed to present themselves to 

 this conclusion. 



It must be postulated that in chemical processes the bodies sharing in 

 the action react with one another in definite equivalent quantities. 

 This proposition appeared, however, not to hold in the case of the 

 action of antitoxine on diphtheria toxine. When, in the case of 

 diphtheria toxines of different stocks, that quantity of toxine bouillon 

 which is exactly n.-^utralised by a certain definite quantity of diphtheria 

 •antitoxine (the official German immunity unit, as laid down for the 

 control examination of sera), was determined, so that every trace of 

 toxic action was abolished, the figures obtained were not in accord. 

 Of one toxine bouillon 0*2 c.c, of another 2*5 c.c, were so neutralised 

 by one immunity unit. Such a relation need not have given rise to 

 surprise, because it was well known that the diphtheria bacillus, 

 according to outside circumstances, yields in the bouillon very dif- 

 ferent quantities of toxine. It was therefore allowable to infer 

 that the different quantities of toxine bouillon, which were saturated 

 by one immunity unit, were exact expressions of the toxicities of the 

 various bouillons, or, to use other words, indiff'erently whether the 

 bouillon was strongly or feebly toxic, the same multiple of the minimal 

 lethal dose would be constantly neutralised by one immunity unit, 



* Note during revision. — The credit of first drawing attention to these points 

 belongs to Professor Eraser, who, as far back as 1896, carried out extraordinarily 

 precise experiments on the conditions of neutralisation in respect both of time and 

 of amount of snake-poison and anti-venin (Lecture, Eoyal Institution, March 20, 

 1896). 



