174 SPECIAL BACTERIOLOGY 



occurring in man from absorption of abnormal products of fermenta- 

 tion from the intestinal canal. An auto-intoxication whereby the 

 resistance of the individual to infection by the typhoid bacillus, should 

 it gain access to the alimentary tract, is reduced. 



BACTERIUM COLI COMMUNIS. 



(Bacillus Neapolitanus. The Colon Bacillus.) 



This bacillus is a normal inhabitant of the intestines of man, 

 cattle, swine, and dogs. It is also found associated with diseased 

 conditions, such as inflammatory and suppurating processes in the 

 peritoneal cavity, infectious enteritis, affections of the liver, puerperal 

 fever, broncho-pneumonia, empyema, endocarditis, meningitis, cystitis, 

 and pyelo-nephritis. 



Microscopical Appearances. Occurs in short motile rods, mostly 

 in pairs (see Photomicrograph, Fig. 64), sometimes in threads, and vacu- 

 oles are frequently present in the middle of the rod as unstained spots. 



Motility. The rods possess numerous long flagella (see Photomicro- 

 graph, Plate II., Fig. 11). 



Spore Formation is absent. 



Staining Reactions. Stains with the ordinary aniline dyes, but 

 not by either the Gram or Cladius method. 



Cultivation. In cultures the organism grows under both aerobic and 

 anaerobic conditions, and in the latter condition forms gas in the media. 



On Gelatine Plates it forms iridescent colonies with wavy bent 

 borders on the surface, while the deeper colonies are round and of a 

 brownish colour ; the gelatine is not liquefied. 



In Gelatine Stab Cultures it grows in the form of a nail with limited 

 growth along the track of the needle (see Photograph of Culture, Fig. 63). 



On Agar-Agar it forms a grey coating. 



On Potato the growth is of a brownish colour. 



In Bouillon it causes diffuse clouding. 



In Milk Media it causes coagulation, which generally takes place in 

 about thirty-six hours. 



Special Reactions. Indol is formed by adding 1 c.c. of a 2 per 

 cent, solution of potassium nitrite and a little sulphuric acid to 10 c.c. of 

 a bouillon culture, when a rose-red colour results. It also produces indol 

 in Dunham's peptone solution in forty-eight to seventy-two hours. This 

 organism also causes fermentation in milk sugar, grape sugar, and 

 glycerine media. 



On Lactose-Litmus- A gar, the colour of the colonies is pink, and that of 

 the surrounding medium blue-red. 



Pathogenesis. Affects mice, guinea-pigs, and rabbits, the strength 



