CHAPTER VII. 

 SIGNIFICANCE OF THE PRESENCE OF B. COLI IN WATER. 



TEN years ago the B. coli of Escherich occupied a posi- 

 tion of very great prominence in the eyes of sanitarians. 

 If it was not considered to be in itself a dangerously patho- 

 genic germ, it was at least regarded as a suspiciously close 

 relation of the typhoid organism. At this time, therefore, 

 the alleged presence of either of these forms was quite 

 sufficient to condemn a water-supply. 



Investigation soon showed, however, that the Bacillus 

 coli was by no means confined to the human intestine. 

 Dyar and Keith (Dyar and Keith, 1893) found it to be the 

 prevailing intestinal form in the cat, dog, hog, and cow. 

 In the goat and rabbit they reported that no single organ- 

 ism was constantly present; and in the case of the horse, 

 the place of the colon bacillus was taken by a new form, 

 described by the authors under the name of B. equi intes- 

 tinalis. About the same time, Fremlin (Fremlin, 1893) 

 found colon bacilli in the feces of dogs, mice, and rabbits, 

 but not in those of rats, guinea-pigs, and pigeons. Smith 

 (Smith, 1895) recorded the presence of the same or- 

 ganism, in almost pure cultures, in the intestines of dogs, 



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