IMMUNITY AND SUSCEPTIBILITY. 555 



animal are protective and in many cases curative. According to Ehrlich, 

 toxins are assumed to possess two combining groups, one known as the 

 haptophore group, which combines with the cells, and another known as the 

 toxophore group, which combines with the cell after the haptophore group 

 has combined and thus produces an intoxication of the cell. The hapto- 

 phore group of the toxin molecule is thermostabile (heat resistant) and the 

 toxophore group is thermolabile (heat susceptible). When a toxin is in- 

 jected into the body of an animal, or is produced during the process of an 

 infection, the haptophore group combines with the cells for which it 

 has an especial affinity and with the receptors (chemical substances which 

 are unsaturated and open to combination with other chemical substances) 

 of these cells. These chemical receptors of the cells with which the toxin 

 haptophore group combines are designated as haptophile receptors. It is 

 probable, also, that the toxophore group of the toxin combines with other 

 chemical receptors in the cell after the haptophore and haptophile groups 

 have combined. These are designated as toxophile receptors. The 

 haptophore receptors of the toxin having combined with the haptophile 

 receptors of the cells, the toxophore group of the toxin then combines and 

 intoxicates, stimulates or sometimes kills the cells, depending on the 

 affinity for the cells and the concentration of this group. In case the 

 cell is not killed, it is stimulated and begins to return to its normal functions. 

 All the available receptors of the cells having been occupied and combined 

 with, the cells set about to generate new chemical receptors in order that 

 food substances and other chemical substances may be taken up. The 

 cells produce these haptophile receptors in excess, that is, there is over- 

 compensation, and they are subsequently excreted into the lymph and 

 blood. These haptophile receptors are, in fact, the chemical substances 

 which we know as antitoxins. It is not only the cells with which both the 

 haptophore and toxophore groups of the toxin combine, because of special 

 affinity, which make all the antitoxin, but cells which are widely separated 

 from those which have an especial affinity for the toxin, also produce 

 antitoxin. For example, tetanus toxin has an especial affinity for nerve 

 tissue, but this tissue produces little of the antitoxin. In this case most 

 of the antitoxin seems to be produced in the spleen, lymph glands, and 

 bone marrow. The haptophore groups of the toxin have at least com- 

 bined with these cells and stimulated them to the overproduction of 

 haptophile receptors. 



It has been mentioned that the antitoxins are protective to the body 



