IV 



Dosis minima lethalis Toxicity 



The original diphtheria toxin 0,0027 cc. 370 



The fluid covering the gelatine 0,004 250 



The upper solid layer 0,01 100 



The second 0,048 21 



The third 2,0 0,5 



The layers below where not toxic at all. The fluid 

 was covered with a thin stratum of mould, which 

 would seem not to have affected it in any way. 



The toxicity of the above dosis minima lethalis can 

 be calculated by simply taking their reciprocal values. 

 The sum total of the toxicity of all the layers examined 

 is 371.5, which is the same as the toxicity of the origi- 

 nal diphtheria toxin, allowing for errors of experiment. 

 It appears from this that no change has taken place 

 in the diffused toxin neither through the mould, nor 

 the gelatine, nor through the deterioration owing to 

 time or any other circumstance. 



Similar experiments were undertaken with diph- 

 theria-antitoxin, tetanolysin and antitelanolysin; and from 

 these experiments the following constants of diffusion 

 were calculated: 



Diphtheria-toxin K == 0,0142 



Diphtheria-antitoxin K = 0,00149 



Tetanolysin K == 0,();!(i(i 



Antitetanolysin K = 0,00205 



It appears that the constants of diffusion for the two 

 antitoxins are much smaller than those of the toxins, 

 indicating that the molecular weights of the antitoxins 

 are very much greater than in the case of toxins. This 

 quite corresponds to our present ideas about the rela- 

 tive size of these bodies. 



While the above constants of diffusion give a re- 

 presentation of the velocity of diffusion of the bodies 



