Xx. 
BACTERIA IN DIPHTHERIA. 
DIPHTHERIA is generally recognized by physicians as a specific 
infectious disease, and, owing to its wide prevalence and fatal char- 
acter, a precise knowledge of its etiology is of the greatest import- 
ance. Until, as a result of recent researches, this was determined, 
pathologists were in doubt as to whether diphtheria should be con- 
sidered as primarily a local infection, or whether the local manifesta- 
tions were secondary toa general systemic infection. But this question 
appears now to be definitely settled in favor of the former view. We 
have to-day a very precise knowledge of the specific infecting agent, 
and have evidence that it produces during its growth. a very potent 
toxic substance, the absorption of which from the seat of local infec- 
tion accounts in a satisfactory manner for the general symptoms of 
the disease, which are due to toxzemia and not to an invasion of the 
blood and tissues by the pathogenic microérganism producing it. 
Numerous researches by competent bacteriologists have failed to 
demonstrate the presence of bacteria in the blood of patients suffer- 
ing from diphtheria, but a variety of microdrganisms have been ob- 
tained in cultures from diphtheritic pseudo-membranes, and may be 
demonstrated by the microscopical examination of stained prepara- 
tions. Among these are the well-known pus organisms, and espe- 
cially the Streptococcus pyogenes, which appears to be very commonly 
present, and is perhaps the active agent in the production of certain 
forms of pseudo-diphtheria. But the malignant, specific diphtheria, 
so well known in this country and in Europe, has been demonstrated 
by the recent researches of bacteriologists to be due to a bacillus first 
recognized by Klebs in stained preparations of diphtheritic false 
membranes (1883), and cultivated and described by Léffler in 1884. 
In his first publication Léffler did not claim to have fully demon- 
strated the etiological relation of this bacillus, but this appears to be 
fully established by subsequent researches. 
In his first research Léffler studied twenty-five cases, and in the 
greater number of them found in stained preparations the bacil- 
lus previously described by Klebs. From six of these cases he 
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