Bacillus Xerosis 477 



tiva that it can no longer be looked upon as pathogenic. It 

 is also found upon other mucous membranes than the con- 

 junctiva; thus, Leber found it in the mouth, the pelvis of 

 the kidney, and in intestinal ulcers. From the investigations 

 of Sattler, Frankel and Franke, Schleich, Weeks, Fick, Baum- 

 garten, and others it appears that Bacillus xerosis is a harm- 

 less saprophyte that is occasionally found upon the con- 

 junctiva. Happening to be found in xerosis it was accorded 

 undue distinction. 



Morphology. It resembles Bacillus diphtheriae very 

 closely, but is probably a little shorter. The ends are clubbed, 

 and in them metachromatic bodies are stained by Neisser's 

 and Roux's methods. 



There is no motility; there are no flagella and no spores. 



Cultivation. Upon Loffler's medium and other media 

 commonly used for the diagnosis of diphtheria, the organism 

 grows with so close resemblance to the Bacillus diphtheriae as 

 to make the differentiation difficult. Transplanted to other 

 media, it continues to resemble B. diphtheriae. 



Chemistry. The organism is incapable of forming any 

 toxin. It ferments sugars like Bacillus diphtheriae, with the 

 exception of saccharose, which B. xerosis ferments, but which 

 B. diphtheriae cannot ferment. B. xerosis also fails to fer- 

 ment dextrin, which B. diphtheria ferments. 



These sugar-decomposing properties form the most reliable 

 methods of differentiating Bacillus diphtheriae, B. hofmanni, 

 and B. xerosis. 



Pathogenesis. The organism is not pathogenic for 

 man and is certainly not the cause of xerosis. It is not toxi- 

 cogenic and is not known to be pathogenic for any animal. 



