NEUTRALISATION OF TOXIN 193 



more stable haptophore groups. That the neutralisation 

 of toxin by antitoxin is due to some sort of union between 

 the two, though not necessarily chemical combination 

 in the strict sense, seems to be proved by the work of 

 Martin and Cherry. Brodie, 1 and Martin and Cherry, 2 

 making use of a Chamberland filter, the pores of which 

 had been rendered very fine by saturating with gelatin, 

 found that toxin would pass through such a filter but 

 that antitoxin would not, presumably because the molecule 

 of the latter is larger. By mixing diphtheria toxin and 

 antitoxin in such proportion that the latter was in suffi- 

 cient quantity to neutralise the toxin, and subjecting the 

 mixture to filtration through a gelatin filter, the filtrate 

 was found to be non-toxic. Now since toxin can pass 

 through such a filter, the inference is that the toxin has 

 united with the antitoxin. Using snake-venom and its 

 anti-serum, anti-venin, another method was employed. 

 The anti-venin is destroyed by heating to 68 C. for ten 

 minutes, while the toxic properties of the venom are 

 unaltered by this treatment. By making mixtures of 

 venom and anti-venin, and, after a certain time has elapsed 

 for the interaction to take place, heating to 68 C. for ten 

 minutes, it was found that the mixture is non-toxic, 

 pointing to the union of the toxin (venom) with the anti- 

 toxin (anti-venin). Calmette had performed the same 

 experiment but with a different result, finding his mix- 

 tures still toxic after heating. Calmette, however, treated 

 his solutions almost immediately after mixing, and Martin 

 and Cherry point out that a certain time must be allowed 

 to elapse for the interaction to take place and noted that 

 moderate warming hastens it, as is the case with all 

 chemical interactions. For instance, they found that 

 one mixture of venom and anti-venin allowed to interact 



1 Journ. of Path, and Bad., 1897, p. 460. 



2 Proc. Roy. Soc. Lond., vol. Ixiii, 1898, p. 420. 

 M.B. 13 



