16 EXPERIMENTAL RESEARCHES 



into their two components. The antitoxin, 

 then, exercises its curative influence merely by 

 anchoring the distributive group of the toxins. 



When we speak of monotropism or specificity 

 in the case of antigens and antibodies, we of 

 course mean only the chemical relations between 

 haptophoric groups and receptors. For example, 

 toxins may be specific and yet act upon the cells 

 of all species of animals, if the toxin-anchoring 

 receptors be widespread amongst them. The 

 other extreme we find in those cases in which 

 the organism itself reacts to elements intro- 

 duced into it and forms substances, antibodies, 

 which act on the corresponding antigens ; we 

 are here dealing with antibodies which are 

 specifically monotropic, just as the antitoxins 

 are, and which affect only those substances to 

 which they owe their origin. The only difference 

 is that the antitoxins act by localisation alone 

 when they have anchored the toxins their work 

 is done. The other antibodies, it is true, act at 

 first in a similar way on the substances sensitive 

 to them ; but they have a further action on the 

 anchored substances, an action which is either 

 direct, as in those cases (agglutinins and pre- 

 cipitins) in which, like the toxins, they have 

 special ergophoric groups, or indirect, in that 



