ADSORPTION 167 



of paper, porcelain, etc., with anilin dyes, in the " adsorption " of 

 substances by colloids, etc., 1 and this view is supported by Bordet 

 and Gengou. Thus, when solutions of arsenious acid are shaken 

 up with colloidal ferric hydroxide, a portion of the arsenic is taken 

 up by the ferric hydroxide and a portion remains in solution. 

 Moreover, more arsenious oxide is taken up by the ferric hydroxide 

 from dilute than from concentrated solutions ; this has its counter- 

 part in agglutination. Again, when an antitoxin is added to a 

 toxin in just sufficient amount to produce a non- toxic solution, the 

 amount of toxin which must then be added to constitute a fatal 

 dose is greater than the minimum lethal dose without antitoxin. 

 This is also found to be the case with ferric hydroxide and arsenious 

 acid ; if ferric hydroxide and arsenious acid are mixed so as to form 

 just a non-toxic mixture, the amount of arsenious acid which must 

 then be added to render the mixture toxic is greater than the toxic 

 dose of arsenious acid. 2 



If pieces of filter-paper be placed in a dilute solution of stain at 

 sufficiently long intervals, the pieces first immersed will become 

 coloured while those last immersed will remain colourless. On the 

 other hand, if all the pieces be simultaneously placed in the solution 

 they all become coloured to the same degree. This is exactly 

 comparable to the Danysz effect. All the phenomena of the toxin- 

 antitoxin reaction seem best explained on the adsorption hypothesis 

 of Bordet. Specificity, it is true, is not completely explained 

 thereby, nor is it explained by any other hypothesis. 3 



The antitoxic constituent of antitoxin seems to be a protein 

 body, probably allied to globulin, and, as already mentioned, the 

 globulin content of the blood of an animal treated for antitoxin 

 production increases in some cases. Tizzoni, by precipitating the 

 antitoxic serum by saturation with magnesium sulphate at 30 C., 

 obtained the antitoxin in the precipitate. By partial saturation of 

 antitoxic serum with ammonium sulphate, the antitoxin is carried 

 down with the second precipitate, that is, with the pseudo-globulin 



1 " Adsorption " is physical in nature and mainly due to surface 

 condensation. 



2 See Findlay, Physical Chemistry and its Applications in Medical 

 and Biological Science, 1905. 



3 On the toxin-antitoxin reaction see Craw, Proc. Roy. Soc. Lond., 

 B. vol. Ixxvi, 1905, p. 179 ; Journ. of Hyg., vol. vii, 1907, p. 501 ; and 

 ibid. vol. ix, 1909, p. 46 ; Arrhenius, Immuno-chemistry, 1907, and 

 Journ. of Hyg., vol. viii, 1908, p. 1 ; Madsen, Brit. Med. Journ., 1904, 

 vol. ii, p. 567 ; Bordet, Ann. de VInst. Pasteur, xvii, p. 161 ; McKendrick, 

 Proc. Eoy. Soc. Lond., B, vol. Ixxxiii, 1911, p. 493 ; Gengou, Journ. of 

 State Med^ xx, 1912, pp. 65 and 141 (Bibliog.) 



