Artificial immunity against toxins 361 



The antidiastatic serums also act in vitro and, as their effect can be 

 demonstrated on soluble ferments placed in contact with unorganised 

 bodies, such as gelatine and casein, the purely chemical character of 

 the reaction is all the more strikingly shown. We are indebted to 

 von Dungern, Briot and Morgenroth for accurate observations on this 

 subject. 



Martin and Cherry 1 made use of a different method to demon- 

 strate the direct action of antitoxins on toxins which exhibit their 

 toxic power on the animal organism. They chose snake venom mixed 

 with an ti venomous serum. The mixtures were filtered under great 

 pressure [50 atmospheres] through a film of gelatine, under the idea 

 that, if the venom and antitoxin were not chemically combined, the 

 former alone, owing to its much smaller molecules as compared with 

 those of the anti venom, would pass into the filtered fluid. This fluid 

 should, under these conditions, possess a toxic power for animals, 

 when the mixture, used for filtration, was deprived of the larger 

 molecules. Martin and Cherry left the venom and the antitoxic 

 serum in contact for periods of varying length, before filtering the 

 mixtures. As the result of a series of such experiments carried out 

 according to this scheme, they found that the product of the filtra- 

 tion made after some minutes' contact between the two substances, 

 was distinctly toxic ; whilst the filtrate obtained after a contact of 

 half-an-hour was absolutely innocuous. From their observations 

 these authors conclude that the antitoxin enters into chemical com- 

 bination with the venom, but that the combination does not take 

 place instantaneously, a certain amount of time being necessary for 

 its accomplishment. 



In addition to the time factor others have an influence on the 

 combination between toxins and antitoxins, as is seen from Ehrlich's 2 

 and Knorr's 3 investigations. Both observers have shown that anti- 

 toxin neutralises the toxin more slowly in dilute solutions than in 

 more concentrated form. For this reason, when animals are injected [380] 

 with very weak solutions, the toxin may manifest its action before it 

 can be neutralised by the antitoxin ; this may lead to erroneous 

 conclusions. On the other hand, according to data furnished by 

 these authors, temperature also exerts an influence on the combi- 



1 Proc. Roy. Soc. London, 1898, Vol. LXIII, p. 423. 



2 Klin. Jahrbuch., Berlin, 1897, Bd. vi, S. 13 [of reprint]. 



3 Fortschr. d.Med., Berlin, 1897, Jahrg. xv, S. 657; Miinchen. med. Wchnschr., 

 1898, S. 321. 



