904 Popular Editions of Station Bulletins of ttie 



With the second pair of animals, the cell content of the milk of 

 both remained nearly constant throughout the test, the one high 

 count being in the milk of the check cow. 



With the third pair, also, the fluctuations in cell count were 

 greater with the cow milked without vacuum changes; and the 

 number for the experimental animal was as low at the high-vacuum 

 milking as at the start or at any time during the test. 



These data manifestly show no evidence of " leucocytosis." 



Two fresh cows were milked by hand for one week and two and 

 one-half weeks respectively, and then by machine. The average 

 cell content for the last four or five days of hand milking was 510.000 

 for one cow and 95,000 for the other; and the corresponding averages 

 for the first four days of machine milking were 230,000 and 55,000. 



Part of the animals in the Station herd are milked by hand 

 regularly, part by machine, which made it possible to compare 

 quite large numbers of normal samples of milk taken by each method 

 of drawing. Of such samples, 56 from hand milking had an average 

 cell content of 381,000, and 113 from machine milking 309,000. 



The facts that half of the Station herd has been milked by machine 

 for years and that the herd as a whole gives a lower average cell 

 count than any other herd examined, appear to confirm the other 

 evidence that machine milking, by the vacuum type of machines, 

 does not increase the cell content of milk or tend to draw cells from 

 the interior of the udder. 



The investigations in the Station herd and others 



Do high cell have not demonstrated that any relationship exists 



counts mean between the number of cells discharged and specific 

 unwholesome bacterial infections of the udder. None of the 

 milk? cows in these herds gave " gargety " milk at any 



time, thus making it impossible to study the influ- 

 ence of that particular udder trouble on cell counts. Some of the 

 cows had aborted, however, and others had previously suffered from 

 diseased udders; but in these cases no consistently high cell counts 

 or abnormal fluctuations were noted that were not duplicated or 

 exceeded in milk of cows apparently normal in every way. 



Many udders or quarters of udders showed the presence of large 

 numbers of bacteria of a type undistinguishable by any cultural 

 methods from those producing inflammation of the udder; but the 

 cell counts of the milk when these bacteria were present were some- 

 times large, sometimes small; so that the evidence so far obtained 

 makes it impossible to decide whether or not the discharge of large 

 numbers of cells in connection with particular types of bacteria has 

 any sanitary significance. 



The studies of the cell content of milk made by the 



Conclusion. Prescott-Breed method appear to prove the accuracy 



and utility of the method; they have made it very 



evident that the presence of large numbers of cells in milk does not 



