128 ILLINOIS DAIRYMEN'S ASSOCIATION. 



from the germ-rich udder and flanks of the cow every movement of the 

 cow during milking dislodges some of these forms and they fall into the 

 milk. 



If a surface is moist such movement is not possible, and this teaches 

 us how this factor of pollution can be greatly reduced. If the bag and 

 flank is thoroughly moistened so as to prevent Aislocigment of these dust 

 moats, the difficulty would be largely removed. In an experiment con- 

 ducted by the speaker where an animal was milked under ordinary condi- 

 tions and also where another was washed, the number of bacteria develop- 

 ing on an exposed sterile plate was in the first case over 3,000, while the 

 other was only 115. 



The air of the barn may be replete with bacteria from' the dirty feed, 

 as hay and straw, and so a can of milk standing open in the barn during 

 milking may acquire a considerable number of bacteria in this way. The 

 figures actually obtained by test show that tens of thousands fall into an 

 open pail during feeding in comparison with a few hundred or one or two 

 thousands where conditions are more practically controlled. 



Relative Importance of Foregoing Factors. 



No uniform rule can be given that will show the effect of the factors 

 of pollution as they exist in all cases. Naturally at one time one special 

 factor will predominate, while again some other factor assumes more 

 prominence. Perhaps the pollution arising from dirt derived from the 

 animal is subject to most variations. With some patrons no attempt is 

 made to clean the udders of animals even though the same is covered with 

 slime and dirt from wading in stagnant pools and pastures. This factor 

 in the minds of the majority of people is generally regarded as that which 

 furnishes a large quota of organisms to the milk, perhaps the largest num- 

 ber of any. 



In our experiments, however, such has not been the case. The 

 pollution coming from particles falling into the pail is only a small frac- 

 tion, probably less than one-tenth. In all probability this is due for the 

 most part to the fact that our university herd is kept considerably cleaner 

 than the average and therefore this pollution is lessened. 



