HOFMANN'S BACILLUS 



415 



cultural characters are indeed practically identical, but the diphtheroid 

 bacillus is non-pathogenic to the guinea-pig. Robertson and Shennan 

 found that when administered to rats by the alimentary tract it produced 

 certain nervous symptoms which were associated with changes in the brain 

 of the same order as those in general paralysis. Further research on this 

 subject is still necessary. 







i 

 * 



\ 



The term " pseudo-diphtheria bacillus '' is often restricted by 

 writers to an organism frequently met with in tjie throat. 

 This organism, which is also known as Hofmann's bacillus, 

 merits a separate description. 



Hofmann's Bacillus — Pseudo-Diphtheria Bacillus. — This 

 organism, described by ~~ 

 Hofmann in 1888, is 

 probably the same as one 

 observed by Loffler in 

 the previous year, and 

 regarded by him as be- 

 ing a distinct species 

 from the diphtheria 

 bacillus. The organism 

 is a shorter bacillus than 

 the diphtheria bacillus, 

 with usually a single un- 

 stained septum running 

 across it, though some- 

 times there may be more 

 than one (Fig. 117). 

 The typical beaded ap- 

 pearance is rarely seen, 

 and the characteristic 

 reaction with ISTeisser's 

 stain is not given, 



though in old cultures a few granules which stain deeply may 

 sometimes be found. It grows readily on the same media as 

 the diphtheria bacillus, but the colonies are whiter and more 

 opaque. It does not form acid from glucose or other sugars, 

 and is non-pathogenic to the guinea-pig. Involution forms may 

 sometimes be produced by it. It is usually a relatively easy 

 matter to distinguish this organism from the diphtheria bacillus. 



Hofmann's bacillus is of comparatively common occurrence in 

 the throat in normal as well as diseased conditions, including 

 diphtheria ; it seems to be specially frequent in poorly nourished 

 children of the lower classes. Cobbett found it 157 times in an 

 examination of 692 persons examined, of whom 650 were not 





Fig. 117. — Pseudo-diphtheria bacillus (Hof- 

 mann's). Young agar culture. See also 

 Plate III., Fig. 14. 

 Stained with thionin-blue. x 1000. 



