DISTRIBUTION OF THE BACILLUS 411 



longer than those mentioned may be found, and these specially 

 occur in the spaces between the fibrin as seen in sections. 



Distribution of the Bacillus. The diphtheria bacillus may 

 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- 



FlG. 115. 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 methyleue-blue. x 1000. 



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 

 has already been mentioned (p. 219). 



In diphtheria the membrane has a somewhat different 

 structure, according as it is formed on the surface covered with 

 stratified squamous epithelium, as in the pharynx, or on a surface 

 covered by ciliated epithelium, as in the trachea. In the former 



