CHAPTER VI 

 EXCREMENTAL ORGANISMS 



THE estimation of typical excremental organisms in milk is of 

 considerable value because of the general absence of these 

 bacteria in intra-mammary milk; they indicate, therefore, the 

 amount of care exercised in the production and handling of 

 the milk in a rather better manner than the determination of 

 the total number of organisms, but as milk drawn under the best 

 conditions is never absolutely free from excremental organisms, 

 this advantage is merely relative. 



The estimation of the bacteria usually regarded as indica- 

 tive of manurial pollution has not in the past been developed 

 to full advantage because of the somewhat elaborate technique 

 involved, and also because some sanitarians have regarded the 

 excremental bacterial content as being more determined by 

 duration and conditions of storage than by the original pollu- 

 tion. It would, undoubtedly, be of great advantage if some 

 method could be found of determining the manurial pollution 

 of a sample at the time of milking, not only because it would 

 yield precise information as to the condition requiring correc- 

 tion, but also on account of the possible association of tubercle 

 bacilli with the faecal bacteria. Tubercle bacilli grow so slowly 

 in milk in comparison with the typical excremental organisms 

 that any inferential value associated with the determination of 

 the latter is rapidly nullified by the conditions usually obtain- 

 ing in the marketing of milk. 



The organisms commonly used as indicators of manurial 

 pollution are B. coli, B. enteritidis sporogenes, and Streptococci, 

 and of these B. coli is probably the most important and the most 

 easily estimated. English bacteriologists have, on the whole, 



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