IMMUNITY AND IMMUNIZING AGENTS. 



121 



destroyed by heat (60 to 65 C.) while the haptophore group is not de- 

 stroyed, retaining the power of combining with the receptor group of the 

 living cell. The toxophore group is not necessarily simple. LLmay com- 

 prise two or more different groups. Snake poison contains two toxophore 

 groups, one agglutinating red blood cells, the other causing its general tox- 

 icity. Diphtheria toxin also has two toxophore groups, the one causing 

 the acute symptoms and the other, the toxones with a long incubation, 

 causing the later paralyses and cachexias. 



The nature of immunity to these antigens is conceived as follows: The 

 haptophore group is bound to the cell receptor because of a specific affinity. 



r-f 



FIG. 55. Illustrating receptors of the second order, Fig. 54, illustrating receptors of 

 the first order, c, d, The cell receptor with a Zymophore group (d) and a haptophore 

 group (e) capable of combining with disintegrated bacterial substances (/). The Zymo- 

 phore group produces a ferment which acts upon (disintegrates) the bacterial cell or blood- 

 corpuscle, as the case may be, seized upon by the haptophore group. (Journal of the 

 American Medical Association, 1905, p. 1113.) 



As a result this particular side chain or receptor is lost to the living cell and, 

 following Weigert's law of supercompensation in regeneration, the cell 

 replaces this loss by producing many more receptor groups than were pre- 

 viously present. As in the callus following a fracture there is an over- 

 production. In this way such a large number of receptors of one type are 

 produced that they become excessive and the cell thrusts them off into the 

 blood and into the fluids of the body. Here they constitute the specific 

 antibodies and, because of their specific affinity, unite with the haptophore 

 group of toxins and prevent their reaching the cell which they thus protect. 



Therefore, in antitoxic immunity there are three stages: First, the 

 chemical union of the haptophore group of antigen to the receptor group of 



