ANTITOXINS 175 



dissociated by acids. ''^ On dilution of a neutral toxin-antitoxin 

 mixture, a certain amount of dissociation seems to occur, but there is 

 opposition to the view that the law of mass action applies to the re- 

 action between toxin and antitoxin. If toxin is added to antitoxin in 

 several fractions, with some interval of time between each addition, 

 the final mixture is much more toxic than if the same quantities of 

 toxin and antitoxin were put together at one time. This phenomenon 

 is commonly referred to as the Danysz effect, and indicates that the 

 toxin-antitoxin union is physical rather than chemical, for it seems to 

 be quite analogous to such a phenomenon as the taking up of more 

 dye by several pieces of blotting paper added in series to a dye solution, 

 than by the same amount of paper added in one piece. 



There is no relation between antitoxins and enzymes. The anti- 

 toxin acts quantitatively, and produces no detectable alteration in the 

 toxin, or in any other substance, as far as we know. It also has but 

 one functioning group (haptophore), the one with which it combines 

 with the toxin; whereas both toxins and enzymes seem to have two 

 functionating groups, one which unites with the cell or substance that 

 is to be attacked, the other which produces the chemical changes. 

 But there is evidence that union with antitoxin or fixed receptors pre- 

 pares the toxin for its disintegration, which, presumably, is then 

 accomplished by enzymatic action as with other antigens. 



Chemical Nature of Antitoxins*^ 



This is as entirely unknown as is the nature of the toxins. In- 

 vestigation of antitoxic serum (principally diphtheria antitoxin) has 

 shown that the antitoxic properties are closely related to the serum 

 globulin, which, however, by no means proves that antitoxin is serum 

 globulin or any other sort of protein. According to Ehrlich's theory, 

 antitoxin consists of free cell receptors, and these receptors are pre- 

 sumably simple chemical groups which may be but a part of a larger 

 molecule, or they may be entire protein molecules. In any event 

 they behave as colloids; moving toward the cathode in an electrical 

 field, ^^ diffusing little or not at all, their reaction curve resembling 

 more an absorption curve than the reaction curves of crystalloids, and 

 being influenced by all conditions that influence colloids. Whether 

 the receptor groups are secreted in a free condition in antitoxin*^ for- 

 mation, or combined in a large molecule, is unknown. 



By saturating serum with magnesium sulphate, or half saturation 

 with ammonium sulphate, three chief groups of proteins can be pre- 



8« Morgenroth and Ascher, Cent. f. Bakt., 1911 (59), 510. 



'^ Review and bibliography given by Crawford and Foster, Amer. Jour. Phar- 

 macy, 1918 (90), 765. 



88 According to Field and Teague (Jour. Exper. Med., 1907 (9), 86) both \ 

 toxin and antitoxin move towards the cathode, which is opposed to the theory 

 that this reaction is simply one of oppositely charged colloids. (See also Bechhold, I 

 Munch, med. Woch., 1907 (54), 1921.) ' 



