EQUILIBRIA IN ABSORPTION PROCESSES 153 



intuition that it would conflict with experience. Evidently 

 it agrees with the experiments in the shaking of poisons 

 with colloidal hydroxids (except in that these substances 

 are not chemically attacked by the poisons), but it does not 

 harmonise with our experience with the reactions of bac- 

 teria to their agglutinins. 



It may also be emphasised that the solutions of anti- 

 toxins do not behave as suspensions, as is seen in their 

 diffusibility in jelly, which is not observed with suspended 

 particles. 



There is another phenomenon which we encounter in 

 the use of some kinds of agglutinins, e.g. such as have 

 been weakened by acids, or other chemicals, or by heat. 

 These modified agglutinins display an increase in their 

 agglutinating power until a maximum of agglutination is 

 reached. Thereafter new additions of agglutinin dimin- 

 ish the effect and at a high concentration of the agglu- 

 tinin the agglutination ceases. A similar behaviour is 

 characteristic of many salts. Without the presence of 

 some salts in the solution, no agglutination takes place, and 

 the same is also true for very high concentrations of the 

 salts. With increasing concentration of the salt (above the 

 optimum value) a greater quantity of agglutinin is neces- 

 sary to produce agglutination, and at a concentration of the 

 salt above a certain limit value the agglutination fails. 

 On small additions of salts the agglutinated quantity 

 seems to be proportional to the added quantity, which 

 might be expected on the basis of most of the hypotheses 

 regarding the nature of agglutination, and not only from 

 the chemical one, as Joos supposes. 



In the theory of immunity we find many analogous 



