1 82 BACTERIA 



ally influence the number of micro-organisms in the milk 

 than the popularly supposed fermenting food which the 

 animal may eat. It is from this external source rather than 

 from the diet that organisms occur in the milk. The hairy 

 coat offers many facilities for harbouring dust and dirt. The 

 mud and filth of every kind that may be habitually seen on 

 the hinder quarters of cattle all contribute largely to pol- 

 luted milk. Nor is this surprising. Such filth at or near 

 the temperature of the blood is an almost perfect environ- 

 ment for many of the putrefactive bacteria. 



The milker is also a source of risk. His hands, as well as 

 the clothes he is wearing, can and do readily convey both 

 innocent and pathogenic germs to the milk. Clothed in 

 dust-laden garments, and frequently characterised by dirty 

 hands, the milker may easily act as an excellent purveyor 

 of germs. Not a few cases are also on record where it ap- 

 pears that milkers have conveyed germs of disease from 

 some case of infectious disease, such as scarlet fever, in 

 their homes. But under the more efficient registration of 

 such disease which has recently characterised many dairy 

 companies, the danger of infection from this source has been 

 reduced to a minimum. The habit of moistening the hands, 

 with a few drops of milk previous to milking is one to be 

 strongly deprecated. 



Professor Russell recounts a simple experiment which 

 clearly demonstrates these simple but effective sources of 

 pollution : 



*' A cow that had been pastured in a meadow was taken for 

 the experiment, and the milking done out of doors, to eliminate 

 as much as possible the influence of germs in the barn air. 

 Without any special precaution being taken the cow was partially 

 milked, and during the operation a covered glass dish, contain- 

 ing a thin layer of sterile gelatine, was exposed for sixty seconds, 

 underneath the belly of the cow in close proximity to the milk- 

 pail. The udder, flank, and legs of the cow were then thor- 



