180 CHEMISTRY OF THE IMMUXITY REACTIONS 



of the fluid in which the reaction occurs (Zunz),**' and the neutral 

 toxin-antitoxin compound (diphtheria) is not absorbed by animal 

 charcoal, which absorbs each of the constituents when free. The 

 physico-cliemical studies of the reaction between tetanolysin and its 

 antibody gave results which led Arrhenius to conclude that in the 

 reaction there are formed from one molecule of toxin and one molecule 

 of antitoxin, two molecules of the reaction products (analogous to the 

 reaction between alcohol and acid which yields one molecule of ester 

 and one of water). In general, the union of toxin and antitoxin is 

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

 ture, a certain amount of dissociation seems to occur, but there is op- 

 position 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 commonlj' 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 solu- 

 tion, 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 sub- 

 stance that is to be attacked, the other which produces the chemical 

 changes. But there is evidence that union with antitoxin or fixed re- 

 ceptors prepares the toxin for its disintegration, which, presumably, 

 is then accomplished by enzymatic action as with other antigens. 



CHEMICAL NATURE OF ANTITOXINS 



Tliis is as entirely unknown as is tlie 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 coiisists of free cell receptors, and these receptors are pre- 

 sumaljly 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,*^ difiPusing little or not at all, their reaction curve resembling 



40 Bull. Acad. Roval ]\red. Belg., 1!)II: also Bortolini, BicuOiom. Zoit.. 1010 

 (28), 60. 

 47Morgenroth and As*c1icr. Cent. f. Bakt.. 1011 (50), rAO. 

 48 According to Field and Toaprne (.lour. l':\por. Mi'd.. 1007 (0), 80) both 



