400 



DIPHTHERIA 



be found in the membrane wherever it is formed, and may also 

 occur in the secretions of the pharynx and larynx in the disease. 

 It may be mentioned that distinctions formerly drawn between 

 true diphtheria and non-diphtheritic conditions from the appear- 

 ance and site of the membrane, have no scientific value, the only 

 true criterion being the presence of the diphtheria bacillus. The 

 occurrence of a membranous formation produced by streptococci 



Fig. 110.— Film preparation from diphtheria membrane, showing 

 numerous diphtheria bacilli. One or two degenerated forms are seen 

 near the centre of the field. (Cultures made from the same piece of 

 membrane showed the organism to be present in practically pure 

 condition.) ' 



Stained with methylene-blue. x 1000. 



has already been mentioned (p. 211). Virulent diphtheria bacilli 

 have been found in a considerable proportion of cases of fibrinous 

 rhinitis. In the case of any nasal lesion, however, the test for 

 virulence should always be made, as diphtheria-like bacilli 

 without virulence are of comparatively common occurrence. 



In diphtheria the membrane has a somewhat different structure, accord- 

 ing as it is formed on the surface covered with stratified squamous 

 epithelium, as in the pharynx, or on a surface covered by ciliated 



