552 IMMUNITY 



whicli he calls receptors or lateral chains which certain of the 

 cells possess. These receptors are concerned in the normal 

 nutrition of the cells and have affinities for various complex 

 albuminous substances. Among these substances are the 

 molecules of the toxin produced by certain bacteria and pos- 

 sibly other poisons. Every toxin has affinities described as 

 haptophorus and toxophorus, that is, every molecule of the 

 toxin is composed of two different groups of atoms, the one 

 the toxophore or poisonous group, the other the haptophore or 

 combining group of atoms. The haptophorus molecules of 

 the toxin combine or unite with the receptors of those cells for 

 which they have special affinity and through the haptophore 

 group the toxophore part of the molecule is able to act upon 

 the cell. It some cases the cells are destroyed and in others 

 additional receptors seem to be produced because of the stimu- 

 lation. These receptors may pass out of the cell into the 

 serum, where they act as free receptors or immune bodies to 

 lock up or neutralize the toxin. The free receptors are the 

 active part of the antitoxin. 



Ehrlich illustrated his theory by the use of diagrammatic 

 figures to represent the cell throwing off " receptors," the re- 

 ceptors or antitoxin locking up or neutralizing the toxin and 

 the effect of the anti-bodies on the toxin and its complement. 

 The accompanying figures are taken from his work. 



§ 447. Hemolysins. Belfanli and Carbone, in 1898, 

 pointed out the fact that if horses were injected with the red 

 blood cells of rabbits the serum of these horses would be more 

 or less toxic for rabbits. This result was followed with some 

 interesting experiments by Bordet in which he showed that 

 the blood serum of guinea pigs that had been injected several 

 times with from three to five cubic centimeters of defibrianated 

 rabbit's blood acquires the property of rapidly dissolving in a 

 test tube the red blood cells of a normal rabbit's blood. The 

 serum of an untreated healthy guinea pig will not do this. 

 It was pointed out that this reaction was specific, that is, the 

 serum of animals treated with rabbit's blood (specific serum) 

 dissolves the red corpuscles of the rabbit's blood only. This 



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