414 DIPHTHERIA 



conditions — from skin diseases, from coryza, from leprosy, from 

 gun-shot wounds, and even from general paralysis of the insane. 

 As has been found with other groups, the differentiation is a 

 matter of considerable difficulty. Some are practically identical 

 with the diphtheria bacillus both morphologically and culturally, 

 and give the characteristic reaction with Neisser's stain ; others, 

 again, differ in essential particulars. The fermentative action 

 on sugars (p. 404) 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. The absence of the 

 power of fermenting glucose may, however, be accepted in any 

 particular case as sufficient to exclude the organism from being 

 the diphtheria bacillus. 



From what has been said it will be clear that the scientific 

 differentiation of the organism may be a matter of great difficulty 

 — even with the test for virulence, so many gradations are met 

 with. With regard to the rules for practical guidance, there is 

 general agreement as to the two following. In the first place, in 

 cases of suspected diphtheria the obtaining of a bacillus in a 

 serum culture from the throat, which has all the morphological 

 and staining characters of the diphtheria bacillus, may be accepted 

 as a positive result for all practical purposes. And further, most 

 will agree that a similar rule should hold in the first instance with 

 regard to bacilli obtained from the throats of immediate contacts. 

 In the second place, a diphtheria-like bacillus obtained from 

 another part of the body, with or without a lesion, should not be 

 accepted as the diphtheria bacillus, however closely it resembles 

 it, unless it is found on inoculation to produce the characteristic 

 results. In view, however, of the fact that diphtheria-like bacilli 

 without virulence are present in the throats of some healthy 

 individuals, and may also be present along with virulent bacilli 

 in cases of diphtheria, it appears to us that no one should be 

 regarded as a carrier, dangerous to the community, unless the 

 organism in question is proved to possess virulence. Such a rule 

 rests on the assumption that quite avirulent bacilli do not give 

 rise to infection and may be disregarded. The results of the 

 accumulated experience of numerous observers, however, support 

 such a view. 



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 nourish specially in the respiratory and alimentary tracts. 

 It closely resembles the diphtheria bacillus ; the morphological and 



