THE HOFMANN BACILLUS 343 



and Frankel describe the pseudo-diphtheria bacillus as 

 morphologically resembling the Klebs-Loffler bacillus, 

 while Loffler, von Hofmann, Koplick, Park and Beebe, 

 Peters, and Hewlett and Miss Knight, 1 consider that an 

 organism differing somewhat from the Klebs-Loffler 

 bacillus should alone be termed the pseudo-diphtheria 

 bacillus ; to avoid confusion it is best to designate it the 

 Hofmann bacillus. 



Morphology. Typically, the Hofmann bacillus is a 

 shortish rod tapering towards the ends, which are rounded, 

 the average length being from 1-5 p to 2 /x, and it occurs 

 in pairs, resembling two suppositories placed base to base. 

 It is non-motile, does not form spores, is arranged in a 

 parallel grouping like the Klebs-Loffler bacillus (due to the 

 same mode of division), and involution forms are, as a 

 rule, not met with (Plate VII, a). It is Gram-positive, 

 and stains deeply and regularly with Loffler 's methylene 

 blue, segmentation and polar staining usually being absent. 

 With Neisser's stain no inky granules are perceptible, as 

 is the case with the diphtheria bacillus. 



Cultural reactions. The Hofmann bacillus develops 

 well at temperatures from 20 to 37 C., and is almost a 

 strict ae'robe ; there is no growth anareobically in hydro- 

 gen. On serum, agar, and gelatin it forms cream-coloured 

 colonies or growths, barely distinguishable from those of 

 the Klebs-Loffler bacillus ; gelatin is not liquefied. On 

 ordinary potato it hardly grows at all, what growth there 

 is being quite invisible. On alkaline potato, 2 however, it 

 forms distinct cream-coloured colonies, usually visible by 

 the second day. In stab-cultures in gelatin and glucose- 

 agar no gas is formed, and the growth is confined to the 

 upper part of the stab. In broth it forms sometimes a 



1 Trans. Brit. Inst. of Prev. Med., vol. i, 1897. 



2 Ordinary potato rendered alkaline with a 10 per cent;, solution of sodium 

 carbonate before sterilisation. 



