94 DAIRY BACTERIOLOGY 



efficiency of the process should be checked first and foremost by 

 ascertaining whether the number of microorganisms is satis- 

 factorily low, which will be the case if it shows a long time for 

 reduction (at least nine hours) in the reductase test (see p. 166). 

 In this way a double purpose will be served, for the test will 

 only show satisfactorily withjreshly pasteurised milk, and this 

 is exactly what is required, for, unless pasteurised milk is fresh, 

 it will be a source of danger, and should be regarded in the 

 same light as an adulteration, as it purports to be better than raw 

 milk, whereas in reality it is worse. As low temperature pas- 

 teurised milk, like that pasteurised at a high temperature, cannot 

 be relied on to sour spontaneously, it should not be sold as raw 

 milk, but should be plainly marked with the date of pasteurisation. 



The high temperature pasteurised milk which is at present sold 

 in Copenhagen is often as rich in bacteria as raw milk, and always 

 shows copious evolution of gas in the fermenting test on account 

 of its comparatively high content of butyric acid and pseudo 

 lactic acid bacteria. The latter probably find their way into the 

 milk on the open coolers and from unsterilised bottles. The 

 advantages offered by such milk are exceedingly doubtful, and 

 any one who fears the risk of infection had far better buy raw milk 

 and boil it. 



According to the author's repeated investigations, the ice milk 

 supplied to Copenhagen, which was mentioned above (sold from 

 carts at about 9 a.m.), contains on an average 60,000 bacteria per 

 cubic centimetre, and the ordinary milk from large dairies, from 

 several hundred thousand to about two millions. Small dairies 

 generally sell far inferior milk, the counts sometimes running as 

 high as one hundred million organisms per cubic centimetre. 

 Better conditions can hardly be expected without further legisla- 

 tion. The author suggested at the International Dairy Congress 

 at Stockholm 1 that no hard and fast rule should be laid down 

 once and for all as to the maximum number of bacteria and the 

 minimum percentage of fat in different grades of retail milk, but 

 that the dairies should be required to make some guarantee which 

 should be plainly stated on the label in such a way that it could 

 not be misunderstood. Competition would then bring about a 

 gradual improvement in the quality of the milk, and the authorities 

 would only have to see that the dairies did not promise more than 

 they fulfilled. In this way the smaller dairies which can guarantee 

 nothing, would be suppressed, and the trade would pass entirely 

 into the hands of the large and well-regulated firms 2 . 



1 " Maelkeritidende," 1911, p. 731. 



2 The bacteriological condition of the milk retailed in the large towns of 

 the United Kingdom leaves quite as much to be desired. It is to be 



