182 CHEMIfiTRY OF THE IMMUNITY REACTIONS 



to trypsin) and therefore is presumably of similar nature. Anti- 

 toxin seemed to be much more rapidly destroyed by pepsin-HCl di- 

 gestion than by trypsin, in which respect it again resembles the serum 

 globulin. 



In favor of the view that antitoxin is a definite protein body is 

 also the fact that it is not carried down in indifferent precipitates, as 

 are the enzymes, but comes down always in a certain fraction of the 

 protein precipitates, e. g., we can precipitate all the serum albumin 

 from an antitoxic senim, and it does not carry down with it any of 

 the antitoxin. Another important point has been brought out by 

 Arrhenius and Madsen,^* who determined approximately the mo- 

 lecular weight of toxin and antitoxin by moans of their rate of dif- 

 fusion, and found that the toxin (diphtheria toxin and tetanolysin) 

 diffused ten or more times as rapidly as the corresponding antitoxin. 

 Gelatin filters also hold back antitoxin and let toxin pass through, and 

 toxins diffuse into cells which seem to be impermeable for the anti- 

 toxin. This indicates that the antitoxin molecules are much larger 

 than the toxin molecules, agreeing with the idea that antitoxin is of 

 protein nature and that toxin either is not protein or is smaller than 

 most protein molecules. 



Taken altogether, the evidence indicates a closer resemblance of 

 antitoxins to proteins than has been shown for the toxins, and all 

 attempts to separate antitoxins from proteins have so far failed. 



Antitoxins are retained to greater or less extent by porcelain 

 filters, do not pass through dialyzing membrances readily, and are in 

 general easily destroyed by chemical and physical agencies, although 

 much less so than are most toxins. Heating to 60°-70° injures, and 

 boiling quickly destroys them, although like the enzymes and the pro- 

 teins, they resist dry heat to 140°, and also extremely low tempera- 

 ture, without change. Putrefaction of the serum destroys the anti- 

 toxins (Brieger).^^ They can be preserved for a very long time when 

 dried completely, but in the serum they gradually disappear, espe- 

 ciall}^ if exposed to light and air. Acids and alkalies destroy anti- 

 toxins, acids being the more harmful in low concentrations. Like the 

 enzymes, antitoxins are destroyed by ultra-violet rays. They are 

 destroyed in the alimentary tract, without appreciable absorption, 

 except in the case of new-born animals sucking mothers whose blood 

 and milk contain antitoxin.^" Wlien subcutaneously injected, anti- 

 toxin soon disappears from the blood ; part may be bound to the 



C4 Festskrift, Siatons Soniin Iiislitul. 1902. 



5H Bf]irin<r stalos tliat totanua aiiiitoxin rosists piitrofnotion. 



66 Rr.mor and Much, .Talirb. f. Kindorlioilk.. lOOfJ (0.3). fiS4 : "^rcClintock and 

 Kinp f.Tf)iir. Tnfoct. Dis., mOfi (.3). 701) found api)roci:il(lo absorption of antitoxin 

 ■when di<,'-cstif)n was impaired by drufrs. Full ivviow of literature on transmission 

 of antibodies from niotlier to od'sprins: sjiven bv I'^ainulener, Jour, hifeet. Dis., 

 1912 (10), 332: IbMirlin, .\reli. Mens. Obs! et Gyn., I!tl2 (1). 407. 



