66 BACTERIA 



The latter rarely occur in the intestine, but may be seen in 

 fluid cultures. The common site for Koch's comma is in the 

 intestinal wall, crowding the lumina of the intestinal glands, 

 situated between the epithelium and the basement membrane, 



The Comma-Shaped Bacilli of Cholera 



abundant in the detached flakes of mucous membrane, and 

 free in the contents of the intestine. They do not occur in 

 the blood, nor are they distributed in the organs of the 

 body. 



The bacilli are actively motile, and possess at least one 

 terminal flagellum. The organism is aerobic, and liquefies 

 gelatine. It stains readily with the ordinary aniline dyes. 

 It does not produce spores, though certain refractile bodies 

 inside the protoplasm of the bacillus in old cultures have 

 been regarded as such. The virulence of the bacillus is 

 readily attenuated, and both the virulence and morphology 

 appear to show in different localities and under different 

 conditions of artificial cultivation a large variety of what 

 are termed involution forms. Unless the organism is con- 

 stantly being sub-cultured, it will die. Acid, even the .2 per 

 cent, present in the gastric juice, readily kills it. Desiccation, 

 55^^ C. for ten minutes, and weak chemicals have the same 

 effect. The bacilli, however, have comparatively high powers 

 of resistance to cold. Unless examined by the microscope 



