The " Lateral-Chain Theory " of Immunity 1 2 1 



parative insensitivity or insusceptibility upon the fact that 

 the greater number of haptophore groups are attached to 

 comparatively unimportant cells whose combining affinities 

 have to be satisfied before combination with more vital cells 

 can be accomplished. In some cases natural immunity is 

 increased by the presence of free haptophore groups (anti- 

 toxin) in the blood. 



Acquired immunity against toxins depends upon the 

 regeneration of the cellular haptophores or receptors which, 

 being liberated into the body juices, fix the haptophores of 

 the toxin molecules before they are able to reach the cells 

 themselves. Antitoxins and other anti-bodies, including the 

 lysins, consist of liberated cellular haptophores or receptors, 

 the former having a single combining affinity, the latter a 

 double combining affinity, by which they unite, on the one 

 hand, with the cell to be dissolved, on the other with the 

 complement by which it is to be dissolved. Anti-bodies 

 having this double combining affinity have been called 

 " amboceptors" by Ehrlich. They are variously known in 

 different writings as "immune bodies," amboceptors, sub- 

 stance sensibilisatrice, desmon, and fixateur. The "comple- 

 ment" or "addiment" of Ehrlich is also called alexin and 

 cytase. Khrlich conceives every amboceptor and every 

 complement to be specific, but Bordet and others, while 

 admitting that the amboceptor is specific, holds that there is 

 but one complement or cytase. 



It has already been shown that MetschnikofT's primitive 

 conception of phagocytosis, that of the body being defended 

 against the invasive power of the microparasites by the 

 incorporation and digestion of the microparasites, had to 

 be modified to conform to the increasing information upon 

 the immunity reactions. He has persistently clung to the 

 idea that the phagocytes are the essential factors. When 

 invasive organisms enter the body, positive chemotactic 

 influences determine that they are met by a sufficient number 

 of phagocytes to devour and destroy them. If the invading 

 organisms are too powerful and the phagocytes are killed 

 by them and their toxins, the phagolysis or dissolution of the 

 phagocytes liberates their enzymes into the blood. These 

 liberated enzymes now act deleteriously upon the invaders, 

 tending to agglutinate aggregate them in clumps and 

 sensitize them to the future action of the phagocytes by 

 which they may be taken up. Thus, the blood-serum ac- 



