1 54 Immunity 



tophores with the cell-haptophores can be demonstrated in 

 the test-tube by crushing the cerebral substance of a rabbit, 

 and adding tetanus toxin. The toxin becomes fixed by 

 combination with the cell haptophores or receptors, loses its 

 further combining powers and fails to affect animals into 

 which it is subsequently injected. The increased formation 

 of receptors in consequence of repeated stimulation has been 

 shown by the effect of abrin upon the conjunctiva. If 

 dropped into one eye until the conjunctiva is thoroughly 

 immune against its action, the cells of this eye develop a 

 greatly increased capacity for absorbing i. e., fixing the 

 abriri as compared with those of the other eye. Thus if the 

 two conjunctival membranes be dissected out and a certain 

 quantity of abrin triturated with each, the haptophores of 

 the cells of the immunized membrane fix the poison so that 

 it is no longer able deleteriously to affect animals, while 

 no such effect takes place with the other membrane. 



The ability to stimulate the formation of anti-bodies is 

 entirely independent of any toxic action and is entirely the 

 work of the haptophores. This is best shown in the fact that 

 diphtheria toxin that has been heated or otherwise manip- 

 ulated until its toxic action is lost, still retains the power 

 of combining with antitoxin, or of producing anti-bodies. 



The cells furnishing the haptophore groups or receptors 

 whose presence in the blood gives it its antitoxic quality 

 vary in number or quality in different animals. Thus, in 

 the warm-blooded animals the rapidity with which tetanus 

 toxin is anchored to the cells of the central nervous system 

 seems to indicate that those cells, if not the only cells in the 

 body passing the adapted receptors by which it is anchored, 

 are the chief cells by which it is absorbed. In the alligator, 

 however, other cells seem to fix the toxin before it reaches 

 or connects with those of the nervous system, so that the 

 alligator, though immune against the action of the toxin, 

 is able to make antitoxin as well as susceptible animals. 



Each introduction of appropriate anti-body forming sub- 

 stance is followed by an outpouring of the anti-body far in 

 excess of what would neutralize it, so that after a systematic 

 treatment has been carried out for some time, the neutral- 

 izing value of the blood may be a thousand times what would 

 be necessary to neutralize, the total quantity of active sub- 

 stance introduced into the animal. 



Each anti-body is specific in action, as must be evident 



