BACTERIA IN DIPHTHERIA. 373 



that we were two years ago, owing to the large number of important re- 

 searches which have been made in the interim, in saying that the name 

 diphtheria, or at least primary diphtheria, should be applied, and exclusively 

 applied, to that acute infectious disease, usually associated with a pseudo- 

 membranous inflammation of the mucous membranes, which is primarily 

 caused by the bacillus called Bacillus diphtherias of Loftier." 



With reference to the question as to how long after convalescence 

 is established the diphtheria bacillus may be present in the throat 

 of an infected person, Loffler has made the following research (1890). 

 In a typical case a bacteriological examination was made daily from 

 the commencement until fourteen days after its termination. Fever 

 disappeared on the fifth day, and the exudation had all disappeared 

 on the sixteenth day. Up to this time the bacillus was daily ob- 

 tained in cultures, and subsequently nearly every day up to the 

 twenty-fifth that is, for three weeks after the febrile symptoms had 

 disappeared. Roux and Yersin have also obtained the bacillus in 

 cultures from mucus scraped from the throats of convalescents sev- 

 eral days after the disappearance of all evidence of the disease. 



SECOND. The Klebs-Loffler bacillus is found only in diph- 

 theria. In his earlier researches Loffler obtained the bacillus in a 

 single instance from the mouth of a healthy child, and this fact led 

 him to hesitate in announcing it as his conviction that it was the 

 true cause of diphtheria. But in extended researches made subse- 

 quently he has not again succeeded in finding it, except in associa- 

 tion with diphtheria, and admits now that he may have been mis- 

 taken as to the identity of the bacillus found. This seems not 

 improbable in view of the fact that very similar bacilli have been 

 found by various bacteriologists. Thus Von Hoffmann obtained a 

 very similar but non-pathogenic bacillus from the mucus of chronic 

 nasal catarrh and from healthy mucous membranes ; Babes from 

 cases of trachoma, Neisser from ulcers, Zarinko rrom the surface of 

 various mucous membranes. But all of these were shown to present 

 certain differences in their biological characters by which they could 

 be differentiated from the true diphtheria bacillus. 



Welch and Abbott in their comparative studies did not find the 

 Loffler bacillus, "or any bacillus that an experienced bacteriologist 

 would be likely to confound with it." They examined mucus from 

 the throats of healthy children, from those suffering from simple in- 

 flammation of the tonsils and pharynx, and from four cases of so- 

 called follicular tonsillitis. As a result of their investigations they 

 agree with Loffler, and with Roux and Yersin, as to " the great prac- 

 tical value, for diagnostic purposes, of a bacteriological examination 

 of cover-glass specimens and by cultures " of cases in which there is 

 any doubt of the true character of the disease. They say further : 



