BACTERIAL RECEPTORS. 267 



seem to depend on the nature of the amboceptor 

 rather than on that of complement. 



All bacteria which stimulate to the formation Bacterial 

 of bactericidal serums do so because of certain re- 

 ceptors which they possess. These are, of course, 

 analogous to the receptors of erythrocytes which 

 cause the production of the hemolytic bodies in 

 serum. Bacteria have, in addition, many other re- 

 ceptors, some of which cause the development of 

 agglutinins. In the latter instance we speak of the 

 agglutinogenic receptors of the cells, but there is 

 no name of equal convenience which is used to 

 designate the receptors which stimulate to the 

 formation of amboceptors. No two micro-organ- 

 isms contain an identical receptor apparatus; if 

 the contrary were the case their antiserums would 

 coincide in their bactericidal action. Therefore, the 

 cell receptors (amboceptors) with which they unite 

 during immunization differ correspondingly in 

 their cytophilous haptophores. The cytophilous 

 haptophore of the typhoid amboceptor finds its 

 specific counterpart in the typhoid bacillus, and 

 finding no such counterpart in the vibrio of chol- 

 era, the latter can not be sensitized by the anti- 

 typhoid serum ; on this fact depends the specificity 

 of the serum. This conception does not interfere 

 with the explanation of the group reaction among 

 bactericidal serums, for it is conceivable that the 

 colon bacillus, for example, has, in addition to 

 those receptors which characterize the organism, a 

 small percentage of receptors which are identical 

 with those characterizing the typhoid bacillus. In 

 accordance with this possibility an antityphoid 

 serum may well, as it does, show some increased 

 bactericidal power for closely related organisms. 



