MICRO-ORGANISMS IN MILK 305 



In an investigation of several dairy problems the writer, with 

 Luckhardt and Hicks, studied the effect of a brass strainer in a 

 small-top pail similar to the Stadtmueller type. The bacteria 

 were enumerated in 108 lots of milk drawn into the pail with the 

 strainer inserted, and the same number of lots from the same cows 

 on alternate days into the pail without the strainer. The aver- 

 age was 674 bacteria per cubic centimeter without the strainer 

 and 620 with the strainer. The figures are too close to draw con- 

 clusions in favor of either method. Since the strainer increases 

 the work of cleaning the pail and unless properly sterilized would 

 tend to increase the number of bacteria, it seems profitable to 

 omit it in some styles of small-top pails. 



In some pails, as Stocking has shown, the presence of a strainer 

 reduced the germ content, while in others the germ content was 

 increased. The increase of bacteria can be explained only on the 

 hypothesis that the accumulating dirt is broken up 'and carried 

 into the milk by succeeding streams of milk. If the strainer is 

 constructed in a manner which causes the dirt to be washed 

 aside, better results can be obtained with a strainer. If the 

 strainer were of a conical shape the dirt would be washed away 

 from the place where the fresh streams of milk strike. Theoretic- 

 ally a properly constructed conical strainer would seem to be use- 

 ful. Such a strainer was placed on the market, but has apparently 

 not met with much favor. 



The narrow-top pail is clearly a decided improvement over the 

 old-fashioned open pail, inasmuch as the germ content is mate- 

 rially reduced by its use. Cotton strainers seem to be of some 

 benefit if the dirt remains in a place where it is not struck by 

 streams of milk, but if the streams do strike the dirt it is broken 

 up and a portion of it will eventually reach the milk and increase 

 the germ content. 



On the foregoing pages it has been shown that there are im- 

 portant sources of contamination by which the germ content of 

 milk is increased during milking operations. With the intro- 

 duction of milking machines it was hoped that, by conducting 

 the milk from the udder into the pail without exposure to con- 

 taminating conditions, such as dust, filth, and stable odors, these 

 sources of bacterial pollution could be eliminated. Expectations 

 have been realized in a measure, but the machine has introduced 

 factors which need special attention. 



It is obvious that the simpler the construction of machines 

 and utensils, the more easily can they be kept in sanitary condi- 

 tion. The milking machine is rather complicated, and the dif- 

 ferent parts, unless properly cleaned, offer harboring places for 



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