Specificity 423 



Flexner* has made a study of the minute lesions caused by 

 bacterial toxins and especially of the diphtheria toxin, and Council- 

 man, Mallory, and Pearce,t of both gross and minute lesions, that 

 the thorough student should read. 



Specificity. — Herman Biggs,t in an interesting discussion of the 

 occurrence of the diphtheria bacillus and its relation to diphtheria, 

 came to the following conclusions: 



1. "When the diphtheria bacillus is found in healthy throats, 

 investigation almost always shows that the individuals have been 

 in contact with cases of diphtheria. The presence of the bacillus 

 in the throat, without any lesion, does not, of course, indicate the 

 existence of the disease." 



2. "The simple anginas in which virulent diphtheria bacilli are 

 found are to be regarded from a sanitary standpoint in exactly 

 the same way as the cases of true diphtheria." 



3. "Cases of diphtheria present the ordinary clinical features of 

 diphtheria, and show the Klebs-Loffler bacilli." 



4. "Cases of angina associated with the production of membrane 

 in which no diphtheria bacilli are found might be regarded from a 

 clinical standpoint as diphtheria, but bacteriological examination 

 shows that some other organism than the Klebs-Loffler bacillus is 

 the cause of the process." 



Any skepticism of the specificity of the diphtheria bacillus on 

 my own part was dispelled by a somewhat unique experience. 

 Without having been previously exposed to diphtheria while ex- 

 perimenting in the laboratory the author accidentally drew a living 

 virulent culture of the diphtheria bacillus through a pipet into his 

 mouth. Through carelessness no precautions were taken to prevent 

 serious consequences and two days later the throat was filled with 

 typical pseudo-membrane which private and Health Board bacterio- 

 logic examinations showed to contain pure cultures of the Klebs- 

 Loflaer bacilli. 



Some have been led to doubt the specificity of the diphtheria 

 bacillus because of the existence of what is called the pseudo-diph- 

 theria bacillus or bacillus of Hofmann (q.v.). Bomstein§ found 

 that though it was possible to modify the activity of virulent 

 baciUi, and bring back the virulence of non-virulent diphtheria 

 bacilli, it was impossible to make the pseudo-diphtheria bacillus 

 virulent. Denny|| also found that the morphology of the two organ- 

 isms was continually different when they were grown upon the 

 same medium for the same length of time, and that the short pseudo- 

 diphtheria bacillus never showed any tendency to develop into the 



* 'I Johns Hopkins Hospital Reports," vi, 259. 



t "Diphtheria: A Study of the Bacteriology and Pathology of Two Hundred 

 and Twenty Fatal Cases," 1901. 



I "Amer. Jour. Med. Sci.," Oct., 1896, vol. xxii. No. 4, p. 411. 

 § Archiv Russes de Path.," etc., Aug. 31, 1902. 



II American Public Health Association, 1902. 



