CHAPTER XIX. 



BACTERIACE^: THE BACILLUS OF DIPHTHERIA AND 

 OTHER SPECIFIC BACILLI PARASITIC ON SUPER- 

 FICIAL MUCOUS MEMBRANES. 



Bacillus (Bacterium) Diphtherias. Klebs in 1883 discovered 

 this organism in the microscopic study of pseudomembranes 

 from fatal cases of epidemic diphtheria. Loffler in 1884 obtained 

 pure cultures of the bacillus and by inoculating the abraded 

 mucous membrane of susceptible animals with his cultures, he 

 produced local lesions similar to those observed in human diph- 

 theria, in some instances followed by death or paralysis. 



B. diphtheria occurs in the exudate (false membrane) which 

 occurs in the pharynx, larynx and adjacent mucous membranes 

 in epidemic diphtheria, on the mucous membranes of those who 

 have recovered from the disease and, much less commonly, on 

 the mucous membranes of healthy throats. It is a rod-shaped 

 organism extremely variable in size, shape and staining properties. 

 The width is ordinarily between 0.3 and o.8/* and the length 

 varies from i to 6ju. The cell is straight or slightly curved and 

 very frequently of uneven diameter, with swelling at one end or 

 in the middle portion. The cell contents stains unevenly in 

 many of the cells. Many different morphological types are thus 

 presented which may be designated roughly as regular cylinders, 

 clubs, spindles and wedges according to form, and as uniformly 

 pale, uniformly dark, regularly or irregularly banded or granular 

 according to internal structure of the stained cell. These varia- 

 tions in form and internal structure are best seen after staining 

 the bacillus with Loffler's methylene blue and are especially 

 valuable in the quick recognition of B. diphtheria as it grows in 

 the diphtheritic membrane or in culture on Loffler's blood serum. 



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