410 DIPHTHERIA 



difference seems to be one of degree rather than of kind. The 

 absence of the power of fermenting certain sugars, notably 

 glucose, may, however, be accepted in any particular case as 

 sufficient to exclude the organism from being the diphtheria 

 bacillus. From these facts, and from what has been stated 

 with regard to attenuated diphtheria bacilli, it will be seen that 

 an absolute decision as to the nature of a suspected organism 

 may in some cases be a practical impossibility. It may be that 

 some of the " diphtheroid " organisms cultivated have really 

 been non-virulent diphtheria bacilli. The bearing of this on 

 the practical means of diagnosis will be discussed below. 



Ford Robertson and his co-workers have obtained from 

 numerous cases of general paralysis of the insane cultures of a 

 diphtheroid organism, which he considers is the chief agent in 

 producing the condition of chronic intoxication underlying the 

 disease. The organism has been obtained from various situations, 

 including the central nervous system, but it seems to flourish 

 specially in the respiratory and alimentary tracts. It closely 

 resembles the diphtheria bacillus ; the morphological and 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 associ- 

 ated with changes in the brain of the same order as those in 

 general paralysis. Further research on this subject is still 

 necessary. 



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

 present writers to an organism frequently met with in the 

 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 being a distinct species from the diphtheria bacillus. 

 The organism is a shorter bacillus than the diphtheria bacillus, 

 with usually a single unstained septum running across it, though 

 sometimes there may be more than one (Fig. 118). The typical 

 beaded appearance is rarely seen, and the characteristic reaction 

 with Neisser'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 



