524 PATHOGENIC MICROORGANISMS 



n a basis of acid formation was first attempted by Cobbett > and has 

 been recently worked out systematically by Knapp,' and confirmed by 

 various observers.' The results of this work, carried out with the serum- 

 water media of Hiss to which various sugars were added, show that 3 

 Hoffmann! forms acid upon none of the sugars used, while B. diphtheria 





v - v 



-V^A . 



&.*< Li - ; v 



-.^, v:^ --;' 

 "> ^1 



1 \ 



"> > 



> 



FIG. 107. BACILLUS HOFFMANNI. 



acidifies and coagulates media containing monosaccharids and several 

 of the more complex sugars, as given in the diagram in the section fol- 

 lowing, dealing with B. xerosis. 



Differentiation can finally be made on the basis of animal pathogen- 

 icity, B. Hoffmanni being entirely innocuous to the ordinary laboratory 



1 Cobbett, Cent. f. Bakt., 1898. 2 Knapp, Jour. Med. Res., vii, 1904. 



3 Graham Smith, Jour, of Hyg., vi, 1906; Zinsser, Jour. Med. Res., xvii, 1907. 



