92 BACTERIOLOGICAL METHODS 



near future it will be possible to differentiate between pollutions 

 traceable to human origin and such as are traceable to cow, horse 

 or hog manure, for example. It cannot be denied that food 

 materials intended for human consumption which are contamin- 

 ated to any distinctly appreciable amount with the contents of 

 the intestinal tract of any animal, are unsanitary and hence unfit 

 for human consumption. 



In-as-much as the intestinal bacteria (bacilli and streptococci) 

 are very abundant and very widely distributed, it is quite evident 

 that it would be impracticable to pronounce all foods unfit for 

 use if only one or a few intestinal organisms were found to be present 

 in a comparatively large quantity. Human feces contains about 

 one-third bacteria (dry weight), the majority of which belong to the 

 colon group, and the exterior of the human body carries bacteria 

 derived from the intestinal tract, especially the hands and the 

 deposits under the finger nails. Flies are carriers and distributors, 

 of intestinal bacteria. The dust of the streets and street sweepings 

 contain large numbers of bacteria derived from the intestinal tract 

 of the horse, etc. It would be impracticable to enter into a 

 fuller discussion of the distribution of bacteria traceable to in- 

 testinal origin. Suffice it to state that it is the work of the food 

 bacteriologist to determine the presence, in articles intended as 

 food, of those bacteria which indicate contamination with fecal 

 matter, no matter what the source of such objectionable matter 

 may be. The basis for the condemnation of contaminated foods is 

 quantitative in the comparative sense. For example, the finding 

 of a few colon bacilli in large quantities of water or their occasional 

 presence in small quantities of water, does not indicate that the 

 water is unsuitable for drinking purposes. If, however, the colon 

 bacilli appear in a large proportion of many small samples (i cc. 

 or less) of water it is safe to conclude that there is considerable 

 recent sewage contamination and that such water is dangerous 

 to health. The intestinal bacteria are in themselves not seriously 

 pathogenic to man even when taken in considerable numbers. 



