ANTITOXIC AND BACTERIOLYTIC IMMUNITY 51 



cells of the treated eye which neutralized the toxin and rendered 

 it inert. And with tetanotoxin the same has been abundantly 

 proved. This toxin in most animals combines specifically with 

 nerve substance. Take a toxic dose and emulsify it with tri- 

 turated brain substance, and the mixture is inert. 1 As Metch- 

 nikofr" pointed out, 2 the tortoise is not affected by tetanus toxin : 

 after inoculation none is taken up and fixed by the brain or other 

 organs, and no amount of injection of the tetanotoxin will induce 

 the production of antitoxins. Ford 3 also has shown by other 

 methods that antitoxin production only occurs in individuals 

 whose cells have the power of binding the toxin. The full 

 significance of these observations I hope to discuss in the con- 

 cluding lecture of this series. 



But ectotoxin production is a property possessed by a minority 

 of the pathogenic bacteria. The whole group of typho-coli 

 organisms — the causative agents of typhoid and paratyphoid 

 fevers and bacillary dysentery and allied intestinal disorders, — 

 the tubercle and glanders bacilli, cholera spirilla, and the whole 

 group of pathogenic micrococci, whether Gram-positive, like 

 the streptococci and pus - producing cocci, or Gram-negative, 

 like the gonococcus and meningococcus, and the list could be 

 greatly extended : all these, when grown outside the body, do 

 not excrete toxic substances. Yet the body can be immunized 

 against these also, though here the immunity is of a different 

 order. It is not antitoxic, but bacteriolytic. The fluids of the 

 body gain the power of dissolving and digesting the bacteria. 

 The development or acquirement of this power has been gained 

 by all the millions of soldiers in the present war who have been 

 given antityphoid inoculations or, as has been the regulation 

 for more than a year, T.A.B. inoculations — inoculations of mixed 

 vaccines of the Typhoid, Paratyphoid A. and Paratyphoid B. 

 micro-organisms. All this, of course, is perfectly familiar to 

 every one in these days of the great war. By subcutaneous 

 inoculation of carefully measured doses of so many million bodies 

 of dead bacilli, the tissues and fluids of the individual acquire 

 the habit of immediately digesting living bacilli of the particular 

 species employed, and rendering their dissociation products 

 harmless. 



1 See Wassermann and Takaki, Berliner Min. Wochenschr. xxxv., 1895, 5. 

 2 Traite de VImmuniie, Paris, 1901. 3 Zeitschr. f. Hygiene, xl 1902, 363. 



