700 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



the toxin. The antitoxins are labile substances which cannot be 

 analyzed. They may be similar to euglobulins. They are composed 

 of molecules of large size. Antitoxins when present in the body of an 

 animal are protective and in many cases curative. According to Ehr- 

 lich, toxins are assumed to possess two chemical 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 this produces an intoxication 

 of the cell. The haptophore group of the toxin molecule is thermostable 

 (heat resistant) and the toxophore group is thermolabile (heat suscep- 

 tible). When a toxin is injected into the body of an animal, or is pro- 

 duced during the process of an infection, the haptophore group combines 

 with the cells with 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. The 

 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 recepftors 

 of the toxin having combined with the haptophile receptors of the cells, 

 the toxophore group of the toxin then combines and intoxicates, stimu- 

 lates 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 after a time to return to its normal functions. 

 All the available receptors of the cells having been occupied and com- 

 bined with, the cell sets about to generate new chemical receptors in 

 order that food si^bstances 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 



