126 INFECTION AND IMMUNITY. 



and dispose of a greater quantity of bacteriolysin 

 or opsonin; and not only may a bacterium be able 

 to respond to the presence of natural antitoxins in 

 the body by the production of more toxin, the 

 occurrence of which under artificial conditions was 

 shown by Wechsberg in relation to the diphtheria 

 bacillus; but, in addition, certain constituents of 

 our body fluids may, by combining with suitable 

 bacterial receptors, stimulate the bacterium to the 

 production of a whole shower of cytotoxins, which 

 attack the leucocytes, erythrocytes, nerve cells, 

 liver, kidney, etc. The nature of the animal sub- 

 stances which may combine with the bacterial 

 receptors and thus cause the formation of the bac- 

 teriogenic cytotoxins is left an open question and 

 is not of essential importance to the theory; it is 

 not at all necessary that they be toxic to the bac- 

 terium, and they may even be taken up as food 

 substances. Likewise the possible nature of the 

 cytotoxins produced by the bacterium is of second- 

 ary importance. It so happened that "Welch 

 assumed that they might be of the nature of ambo- 

 ceptors which may be complemented by bacterial 

 complement, by the circulating complement of the 

 body or by endocomplements of the tissue cells. 

 One could with equal reasonableness assume that 

 they may be complete toxins, receptors of the sec- 

 ond order, with a haptophorous and a toxophorous 

 structure. 



In some support of this general hypothesis is the 

 observation that the strongest leucocidin (a toxin 

 for leucocytes) can be obtained from the staphylo- 

 coccus by inoculating this organism into a serous 

 cavity of animals, the toxin being obtained subse- 

 quently from the mixture of cocci and leucocytes. 



