BACILLI ALLIED TO DIPHTHERIA BACILLUS 423 



the diphtheria bacillus both morphologically and culturally, and 

 a few even give the characteristic reaction with Neisser's stain ; 

 others, again, differ in essential particulars. The fermentative 

 action on sugars 1 has also been called into requisition as a 

 means of distinguishing them, but the results obtained cannot 

 be said to be of a definite character. It may be stated, however, 

 that most observers have found the diphtheria bacillus of all the 

 members of the group to be the most active acid-producer, 

 though here the 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-vi r ulent 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. 



1 Vide a paper by Graham-Smith, Journal of Hygiene, vi. 286. 



