472 APPLICATION OF METHODS OF BACTERIOLOGY 



obliterated by a marked degree of subsequent alkali 

 production. This fact is of special value in the differentia- 

 tion from bacterium diphtherise. 



BACTERIUM XEROSIS (NEISSER AND KUSCHBERT), 

 MIGULA, 1900. 



Synonym: Bacillus xerosis, Neisser and Kuschbert, 1883. 



Another organism, which is also related in its morphologic 

 and biologic characters to bacterium diphtherise is bacterium 

 xerosis, first encountered by Kuschbert and Neisser in xerosis 

 of the conjunctiva, and which has since been found on the 

 conjunctiva by a number of investigators, in various diseases 

 as well as in health. 



The xerosis bacteria are less likely to be mistaken for 

 bacterium diphtherise because they are somewhat smaller 

 and have less tendency to show multiple striations. Usually 

 they stain deeply at the poles with only one clear unstained 

 band in the centre. It is only occasionally that a few striated 

 organisms are encountered in a culture. 



Biologically bacterium xerosis is readily differentiated 

 from bacterium diphtherise because of the scant growth 

 that takes place on the ordinary culture-media. On agar- 

 agar the growth appears as small transparent colonies which 

 have little tendency to coalesce. On gelatin the growth 

 is slow, and frequently shows as minute, isolated colonies 

 along the needle track. In litmus-milk a slight degree of 

 acidity is produced. In bouillon the growth is so slight as 

 to leave the medium practically unaltered. The growth 

 on potato is slight and invisible. 



