INITIAL CONTAMINATION 373 



lamination in transit, (6) contamination on sellers' or consumers' 

 premises. 



Milk as it is secreted is a sterile fluid, but it is fairly well estab- 

 lished that as it is excreted from the udder it is not sterile. Harding 

 and Wilson examined 1230 samples from the udders of 78 cows 

 which showed an average of 42S bacteria per c.c. The numbers vary 

 widely with different cows, some yielding milk with as few as 25 per 

 c.c., whereas others yielded milk with bacterial contents up to 100,- 

 000. The organisms obtained from the healthy udder are non- 

 pathogenic and are almost invariably staphylococci, streptococci, 

 and other forms of cocci. It is regarded as certain that the origin 

 of these bacteria is from the outside of the teat. They find their 

 way in through the orifice of the teat and extend up the milk column, 

 thus infecting the milk cistern and ultimately the ramifications of the 

 milk tubes through the udder. The work of Savage makes it appear 

 that the number found in freshly drawn milk is determined by the 

 numbers entering the teat, and the selective action of the specific 

 animal. 



The bacteria introduced during the milking process are derived 

 from () the coat, udder, and teats of the cows, (ft) from the milking 

 shed and clothes of the milker, and (c) from the hands of the milker. 

 It is impossible to produce clean milk from cows, the color of which 

 cannot be distinguished even a few rods away because of the filthy 

 condition of their coat. Even where the animal is in a fairly clean 

 condition the wiping of the udder just before milking greatly reduces 

 the number of bacteria in the milk. An average of thirteen experi- 

 ments at the Storrs Experiment Station yielded the following 

 results: 



Bacteria in milk 

 per c.c. 



Unwiped udders 7058 



Wiped udders ... 716 



Decrease due to wiping . 6342 



Numerous investigators have shown the presence of bacteria in 

 large numbers in cowsheds, and many individuals have seen stables 

 or milk houses in which each beam of light passing through the 

 crevices seems to be filled with myriads of dancing specks. These 

 dust particles carry bacteria and will increase the bacteria content 

 of milk. However, recent work at the New York and Illinois 

 Experiment Stations has demonstrated that under fair conditions 

 this is a negligible factor. 



Then the hands of the milker may not be quite clean, or perchance 

 they have come in contact with disease germs from his own or some 

 one's else body, and these may find their way into the milk and at 

 times multiply with an enormous rapidity. 



The influence of the milker in adding bacteria is clearly illustrated 



