BACTERIUM COLI COMMUNE. 357 



Bacterium Coli CJommune (colon bacillus; bacillus 

 Neapolitanus of Emmerich). — This organism was dis- 

 covered by Escherich, in 1885, in the intestinal dis- 

 charges of milk-fed infants. It has since been demon- 

 strated to be a normal inhabitant of the intestines of 

 man and of certain domestic animals (cattle, hogs, dogs). 



For a time after its discovery it was considered of 

 but little importance and attracted attention only be- 

 cause of its resemblance, in certain respects, to the bacil- 

 lus of typhoid fever, with which it was occasionally 

 confounded. In this particular it still serves as a sub- 

 ject for study. Some have even gone so far as to regard 

 them but as varieties of one and the same species, 

 though in the present state of our knowledge this is 

 certainly an assumption for which, as yet, there are not 

 sufficient grounds. That they possess in common cer- 

 tain general points of resemblance and often approach 

 one another in some of their biological peculiarities is 

 true; but, as we shall learn, they each possess peculiari- 

 ties which, when taken together, render their differenti- 

 ation from one another a matter of but little difficulty. 



With the wider application of bacteriological methods 

 to the study of pathological processes it was occasionally 

 observed that, under favorable circumstances, this or- 

 ganism was disseminated from its normal habitat and 

 appeared in remote organs, often associated with dis- 

 eased conditions. This was also, at first, considered as 

 of but trifling moment, and its presence in these locali- 

 ties was usually explained as accidental. Its repeated 

 appearance, however, in different parts of the body out^ 

 side of the intestines, and the frequency of its association 

 with pathological conditions, ultimately attracted atten- 

 tion to it, and in consequence during the past few 



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