IV 



animal experimentation. As a comparison experiments 

 were made with solutions of sodium chloride, which 

 were titrated. 



In the case of 1 n sodium chloride at 6 C we found 

 in this way the coefficient of diffusion 0,95, while this 

 according to Graham ought to be 0,801 and according 

 to Oeholm 0.75. Our value is thus 26.6% to great. This 

 arises from the mode of experimentation, the fluid 

 covering the gelatine pillar being throughout of a simi- 

 lar concentration, while this in the case of the usual 

 mode of experimentation should be smallest where it 

 touches the gelatine pillar. Also the presence of gelatine 

 effects some deviation from the usual course of dif- 

 fusion. As easily will be seen the correction is ever 

 the same, if the diffusion has preceded to the same de- 

 gree. In different cases the correction must only differ 

 but very little, we therefore calculate the velocity of dif- 

 fusion in pure water from the value found after the 

 related method by dividing this value with 1.266. 



On the other side the velocity of diffusion increases 

 with the temperature with about l / so of its value at 

 12 C. for every degree. The velocity of diffusion is 

 therefore 1.25 times as great at 12 C. as at 6 C., the 

 temperature of the ice safe. The velocity of diffusion 

 in water at 12 C. is therefore 1.25:1.266 = 0.986 times 

 greater as the determined value. 



In the case of experiments with diphtheria toxin the 

 height of the fluid covering the gelatine was 1.3 cm. and 

 the pieces into which the gelatine pillar was divided 

 were of a similar height. 



The dosis minima lethalis for guinea-pigs of 250 

 grains weight was determined for the original toxin and 

 for the contents of the test tube; (he following results 

 were obtained: 



