524 



PATHOGENIC MICROORGANISMS 



Cultivation. — On the usual culture media B. Hoffmaimi grows 

 more luxuriantly than B. diphtheriae, developing even in first isola- 

 tions from the human body upon the simple meat-extract media. On 

 agar plates its colonies are larger, less transparent, and whiter than are 

 those of true diphtheria bacilli. In fluid media there is even clouding 



Fig. 108. — Colonies op Bacillus Hoppmanni on Agab. 



and less tendency to the formation of a pellicle than with B. diphtheriae. 

 A positive means of distinction between the two is given by the inability 

 of B. Hoffmanni to form acid upon various sugar media. The differ- 

 entiation on a basis of acid formation was first attempted by Cobbett ' 



' Cobbett, Cent. f. Bakt., 1898. 



