CHAPTER XXII 



BACTERIACE^: THE COLON, TYPHOID AND DYS- 

 ENTERY BACILLI 



Bacillus Coli^- — This organism was probably observed by sev- 

 eral investigators previous to 1886 but it was either neglected or 

 its significance was misinterpreted. The first important study 

 of it was made by Escherich in that year, who discovered it in the 

 feces of healthy infants and obtained it alone on the aerobic gela- 

 tin plates cultures inoculated with this material. 



Fig. 133. — Bacillus coli showing flagella. {From McFarland after Migula.) 



B. coli lives and grows in the intestinal tract of man and mam- 

 mals, and organisms closely resembling it have been found in the 

 intestinal canal of other vertebrates. It is discharged in large 



' For the organisms of the colon-typhoid-dysentery group the Committee of the 

 Society of American Bacteriologists has adopted the generic name Bacterium 

 Ehrenberg 1838, emended Jensen, 1909. Its use in this sense may lead to con- 

 fusion with the genus Bacterium Migula, especially in the minds of beginning 

 students. The old generic name. Bacillus, is therefore here retained. 

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