164 



PRACTICAL METHODS IN IMMUNITY 



consider in an antitoxic serum and that is the protoplasmic particles which are 

 thrown off from the cell in response to the injury incident to the attack upon the cell 

 by the toxin particles. This free particle in the circulation represents the entire 

 mechanism of antitoxic immunity. It is capable of uniting with the toxin molecule 

 and neutralizing its toxic power, or rather so binding its combining end (naptophore 

 group) that it is incapable of attaching itself to a cell, so that the poisonous end of the 

 toxin (toxophore group) cannot have access to the cell. 



The term toxin, strictly speaking, is applicable only to such bacterial 

 poisons as (i) require a period of incubation before being capable of 

 manifesting toxic symptoms and (2) can produce antitoxins. 



For further discussion of toxins and antitoxins see under diphtheria, tetanus, 

 botulism, and pyocyaneus infections. 



FIG. 47. Receptor of third order, and of some substance uniting with one of 

 them. (Journal of the American Medical Association, 1905, p. 1369.) c, Cell recep- 

 tor of the third 'order an amboceptor; e, one of the haptophores of the amboceptor, 

 with which some food substance or product of bacterial disintegration (/) may unite; 

 g, the other haptophore of the amboceptor with which complement may unite; 

 k, complement; A, the haptophore; z, the zymotoxic group of complements. 



Antimicrobic Sera. In antimicrobic sera we have two factors to 

 consider, the first is a prQt.np1f.smfr pajtirlp quite similar to the anti- 

 toxin molecule, but which in itself has no power of injuring its specific 

 bacterium. This particle is generally referred to as the amboceptor or 

 immune body. It is the specific product of the activity of a specific 

 bacterium or foreign cell against the body cells attacked. It with- 

 stands a temperature above q6C. and of itself is incapable of injuring 

 the bacterium in response to whose attack it was produced. The 

 second factor in the bacteriolysis of the specific bacterium, or the haemoly- 



