DIPHTHERIA BACILLUS. 375 



the diphtheria bacilli. If, on the other hand, no cases 

 of diphtheria have been known to exist in the neigh- 

 borhood, even cases of a more suspicious nature would 

 probably not be regarded as diphtheria. 



Appearances Characteristic of Diphtheria. The pres- 

 ence of irregular-shaped patches of adherent grayish or 

 yellowish-gray pseudomembrane on some other por- 

 tions than the tonsils is, as a rule, an indication of the 

 activity of the diphtheria bacilli. Kestricted to the 

 tonsils alone their presence is less certain. 



Occasionally, in scarlatinal angina or in severe phleg- 

 monous sore-throats, patches of exudate may appear on 

 the uvula or borders of the faucial pillars, and still the 

 case may not be due to the diphtheria bacilli; these 

 are, however, exceptional. Thick, grayish pseudo- 

 membranes which cover large portions of the tonsils, 

 soft palate, and nostrils are almost invariably the 

 lesions produced by diphtheria bacilli. 



The very great majority of cases of pseudomem- 

 branous or exudative laryngitis, in the coast cities at 

 least, whether an exudate is present in the pharynx or 

 not, are due to the diphtheria bacilli. Cases in which 

 no exudate is apparent and those in which the laryngeal 

 obstruction is sudden and the spasmodic element is 

 marked, are, however, frequently due to the activity of 

 other bacteria. Nearly all membranous affections of 

 the nose are true diphtheria. When the membrane 

 is limited to the nose the symptoms are, as a rule, very 

 slight; but when the nasopharynx is involved the 

 symptoms are usually grave. Usually a small area of 

 inflammation indicates a slight or moderate severity, 

 and an extensive area a severe infection. 



Most cases of pseudomembranes and exudates entirely 



