IMMUNITY. 



225 



haptophores of antiloxin occupied by the toxin previously added. In this case 

 any additional toxin remains uncombined, and, if such a mixture is injected 

 into a guinea-pig, the animal is killed. 



Bordet's* explanation differs from Ehrlich's. Bordet does not admit the exist- 

 ence of toxons, and regards the paralysis attributed by Ehrlich to the action of this 

 hypothetical substance as due to weakened toxin. He explains the peculiar behav- 

 ior of a neutraUzed mixture of crude toxin with antito.xin, stated above, by assuming 

 that antito-xin is capable of taking up and neutralizing varying amounts of toxin. 



C 60 "!° 



Fig. 54. — " Spectrum" of very fresh crude toxin. 



£00 



He compares the effect of mixing toxin and antitoxin to that of mixing starch and 

 iodine: the more iodine added to the starch, the bluer the color. Let A repre- 

 sent, then, a certain amount of antitoxin; let A be capable of combining r, j, 3, 

 4, 5, different amounts of toxin; call these amounts of toxin Ti, T2, T^, T^, T^; 

 and assume that a combination in vi^hich all the A's are combined with T's in 



JWitoxoid 



•Sytiloxoid 



MemiloTtin 



y//////////////y 



TbxoTi 







Fig. ss-- 



^ 160 200 



-" Spectrum " of crude toxin as it is supposed practically 

 always to occur. 



the proportion of AT^, is neutral, that it has no poisonous properties; that a 

 combination represented by AT, also has no toxic properties, but that AT,, 

 would begin to show toxic properties, and that AT^ is distinctly toxic, and that 

 AT; is very toxic. Starting with toxin, then, if just enough antitoxin is added 

 to neutralize its poisonous properties, AT, is first formed, which is not toxic; 

 now add more toxin, and none of this remains free, but, on the contrary, AT, is 

 formed, which is not toxic; on adding still mor e, when AT^ or AT ^ is reached 



*Bordet. Toxines et Antitoxines. 

 p. 161 ei seq. 

 IS 



Annates de I'lnstitul Pasteur. 1903. 



