108 THE POSSIBLE OCCURRENCE OF [ch. tiii 



the non-Tirulent organism was a direct derivative of the true 

 anthrax bacillus or that it would be capable of giving rise to 

 the latter under suitable conditions. Such a supposition is 

 favoured, firstly, by the admission that the bundle of horse hair 

 from which the B. anthracoides was isolated contained also 

 the spores of true anthrax, and, secondly, by the discovery of 

 Hueppe and Wood some years before (1889) of a similar non- 

 virulent saprophytic anthrax-like organism in earth, which 

 however on injection into a mouse rendered the animal immune 

 to anthrax. 



Similar examples of association between non-virulent and 

 virulent organisms, otherwise closely resembling each other, 

 may be found in the human body — in the intestine B. coli and 

 B. typhosus, in the throat Hoiinann's bacillus and the Klebs- 

 Loeffler bacillus, in the skin the Staphylococcus epidermidis 

 albus and the Staphylococcus pyogenes aureus, in the naso- 

 pharynx the micrococcus catarrhalis and the meningococcus. 



The exact relationship in each case has never been satis- 

 factorily determined. Over twenty years ago Adami (quoted 

 by Arloing, 1891) put forward the suggestion that B. coli might 

 give rise in the presence of fermenting faecal matter to 

 B. typhosus, a theory which has been recently revived by 

 Tarchette (1904) and others (quoted by Hamer, 1909). 



The precise relationship between theviruient Klebs-Loeffler 

 bacillus and Hofmann's bacillus is still a matter of controversy. 

 The latter is a harmless saprophyte not infrequently found in 

 the pharynx of healthy persons. It is distinguished from the 

 true diphtheria bacillus by the somewhat difierent appearance 

 of its colonies on artificial media, by slight and, according to 

 some observers, inconstant diflerences in its morphology and 

 staining, by its inability to ferment glucose and other sugars, 

 and by being non-pathogenic to man and to the guineapig. 

 It has not been found possible to produce immunity against 

 true diphtheria by inoculation with Hofmann's bacillus, and 

 the injection of a filtered broth culture of the latter does not 

 give rise to antitoxin formation in the horse (Petrie, 1905) 

 though the filtrate in the case of even avirulent Klebs-LoefBer 

 bacilli will do so (Arkwright, 1909). Nevertheless many in- 



