328 ANALOGIES WITH DANYSZ' EFFECT 



more toxin. Explanations are also available on the Arrhenius- 

 Madsen explanation, regarding the combinations as examples of 

 mass reaction. 



Regarding reactions such as these as interactions of colloids, 

 we find them paralleled in simple reactions. Thus in some cases 

 the addition to a colloidal solution of a small amount of a second 

 colloid of opposite sign may render the solution more stable, and 

 protect it from precipitation by an excess of the second substance. 

 The partially neutralized aggregates appear to possess more re- 

 pulsive power than those carrying their full electric charge. 

 Again, the effect of an addition of one colloid to another of 

 opposite sign is often brought about slowly, and the material only 

 gradually attains its permanent form. It is probably this fact 

 that renders solutions of antitoxin so unstable. Interreactions take 

 place between the colloids themselves and the electrolytes in the 

 serum, aggregates are formed, and the antitoxic potency falls off 

 rapidly at first and subsequently more slowly. It is a matter of 

 great difficulty to prepare stable solutions of proteid materials. 

 As we have already pointed out, the amount of colloid necessary 

 to precipitate a constant amount of another of opposite sign is 

 reduced to a minimum if the addition be made at once, and 

 rendered much greater if it is made slowly in small amounts with 

 an interval between each. This is closely analogous with the 

 Danysz effect. And this must also be considered in its bearing 

 on Ehrlich's method of attempting to neutralize a certain dose of 

 toxin by successive addition of small amounts of antitoxin, the 

 method by which the whole of the elaborate pluralistic conception 

 of the structure of toxins has been built up. According to the 

 colloidal theory, this is explicable on the assumption that tran- 

 sitional compounds of toxin and antitoxin of very diverse nature, 

 not necessarily dependent on the proportions of the two substances, 

 are formed. This is practically the view put forward by Bordet 

 from a consideration of the reactions of the antibodies, and especially 

 alexin and anti-alexin, and supported by the workers who have 

 examined the question from the standpoint of colloidal reactions. 



The difference between the L and L+ dose, which is so 

 important a feature in Ehrlich's work, also finds an analogy in 

 the reactions of simple colloidal substances. Thus ferric hydroxide 

 neutralizes arsenious acid (whence its use as an antidote in acute 

 arsenical poisoning), and it was found by Biltz that if one lethal 

 dose of the latter substance was added to a neutral mixture of the 



