MICRO-ORGANISMS IN MILK 271 



a more or less abrupt falling off after the fore-milk has been dis- 

 charged, is not definitely known. The germ content of the strip- 

 pings is lower than that of the middle milk according to some au- 

 thorities, while others maintain that it is higher, as a rule. The 

 figures given by Schulz, quoted above, seem to indicate that the 

 strippings contain fewer bacteria than the middle or whole milk. 

 Lux, in an extensive investigation, found the following figures: 



BACTERIA IN FORE-MILK, MIDDLE MILK, AND STRIPPINGS 



No. of Stream. . Middle. Strip- 

 Kind of food. samples. 12 3 pings. Average. 

 Hay mixed with straw, mea', 



bran, etc 60 753 491 1428 1566 367 919 



Hay and malt 100 1396 1637 2066 839 1020 1391 



Grass 



From right back quarter...! „„ fl809 2326 1872 1357 39501 ,„,, 



I From right front quarter,../ °" \l002 1900 1530 743 220/ ^"'^ 



This table shows that the germ content of the first three streams 

 fluctuates and does not decrease gradually. The germ content of 

 the middle milk is sometimes greater than that of the fore-milk 

 and that of the strippings is in two cases greater than that of the 

 previous milk, while in other instances it is smaller. The author 

 thinks that milk accumulates in the ducts and that but little 

 reaches the cistern before milking operations begin. In the 

 different ducts the milk may contain widely varying numbers of 

 bacteria which do not mix with the milk of other ducts until the 

 udder is being emptied. When the milk from ducts that are 

 richer in germ content reach the cistern the counts are higher than 

 when the milk from other ducts is discharged, so that a variable 

 germ content of the product results. 



Similar results have been reported by other authors. Un- 

 fortunately, the precautions for excluding external contamination 

 during the milking process have sometimes not been adequate, 

 so that the results are not always trustworthy. 



Backhaus and Appel, working with great caution, have ob- 

 tained the following results: 



BACTERIAL CONTENT OF DIFFERENT PORTIONS OF MILK FROM THE SAME MILKING 



. Portion. ■ 



No. of cow 12 3 4 



1 685 230 70 30 



2 .. 935 145 20 



4 . 950 60 10 



6 950 110 60 25 



6 375 125 20 45 



7 175 90 60 



8 345 255 55 



Average 631 ' 145 42 14 



According to these figures there is a very consistent falling off 

 in germ content as the milking process advances, and the strip- 

 pings contain the smallest number of bacteria per cubic centi- 

 meter. 



