TOXINS AND ANTITOXINS 179 



'receptors) which are quite different from the groups to which tetanus 

 toxin unites, and hence different receptors are thrown out in im- 

 munizing against each. True toxins have been designated monovalent 

 antigens, since animals immunized with a purified toxin produce only 

 the one antibody, the antitoxin, wliereas many protein antigens pro- 

 duce precipitins, lysins, agglutinins and other antibodies; presuma- 

 bh^ this is because of the relatively small size of the toxin molecule, 

 which limits the number of its antigenic radicals (Pick). Or it may 

 well be that the immune body for antitoxin is quite different from the 

 antibod}' or antibodies resulting from imnumization with non-toxic 

 protein antigens, for there is much reason to believe that the several 

 types of reactions that may be accomplished with the serum of animals 

 immunized to foreign proteins or cells all depend on one single anti- 

 body, which accomplishes the destruction of the antigen by sensitizing 

 it to the enzymes of the blood and tissues. 



The neutralization of toxin by antitoxin is believed by many in- 

 vestigators to be a chemical process, which occurs as well in the test- 

 tube as in the body. It seems to occur according to the laivs of 

 definite proportion, a given amount of antitoxin neutralizing a pro- 

 portionate amount of toxin under equal conditions (hence the toxin 

 is not destroyed by antitoxin through a ferment action, as was at 

 first suggested). Neither the toxin nor the antitoxin is destroj^ed in 

 the process of neutralization, as has been proved by suitable experi- 

 ments, but they appear to be chemically" united to each other, as 

 any two large molecules may be. Pick and.Schwarz believe that the 

 union of toxin and antitoxin takes place in two steps — first, colloidal 

 adsorption, and then the specific reaction.** There is some question 

 as to whether the union with antitoxin completes the neutralization 

 of the toxin, or whether there is then necessary a further destruction 

 of the toxin in the body. But whether necessary or not, such fur- 

 ther destruction does take place. Neutralization occurs more rapidly 

 under the influence of warmth, and more slowly in the cold; and it 

 is more rapid in concentrated than in dilute solutions, just as with 

 ordinary chemical reactions. It is said that it requires two hours 

 for tetanus toxin to be completely combined with the corresponding 

 quantity of antitoxin at 37°. According to Arrhenius and ]\Iadsen, 

 reaction of antitoxin upon toxins is accompanied by the liberation of 

 much heat — 6600 calories per gram molecule, or about half as much 

 as is set free by the action of a strong acid upon a strong base.*^ 

 Union of toxin and antitoxin causes no change in the surface tension 



4-tAlso von Krogh (Zeit. f. Hyg., 1911 (68), 251). Bordet. Biltz.. and others 

 look upon the neutralization of toxin as an adsorption process entirely. 



4-T Literature of cliemioal and physical reactions of toxin and antitoxin triven 

 by Zangger, Cent. f. Bakt. (ref.),'in05 (36), 2.3S; Arrhenius, "Imniuno-ciiem- 

 istry," 1007 and "Quantitative Laws in Biological Chemistry," London. Iftl.T; 

 also review in Zeit. Chemother., Ref., 1914 (3), 157; Oppenheiiner and :\Iicliaelis', 

 Handbuch der Biochemie, Vol. II ( 1 ) . 



