CHAPTER III. 



THE COMMON FORMS OF BACTERIA FOUND IN 

 COWS' MILK. 



THE milk when drawn from a healthy udder being 

 sterile (see p. 23), the kinds of micro-organisms found in 

 the same are dependent on the forms of bacteria found in 

 its surroundings. For this reason we generally find differ- 

 ent kinds of bacteria in different places, and can often form 

 an opinion concerning the company it has kept from a 

 mere microscopic examination of the milk. I shall here 

 only recall a couple of instances described in the preceding. 

 The presence of bacillus sultilis in the milk shows plainly 

 that in some way or other it has been exposed to fodder 

 dust, etc., while the presence of peptonizing, putrefactive 

 bacteria in large numbers indicates that the milk has been 

 in too intimate contact with manure particles and other 

 filthiness. Still more certain pointers as regards the causes 

 of the infection of the milk, are obtained by microscopic 

 examinations of the non-bacterial impurities, as described 

 in the preceding chapter (see p. 31). 



Different forms of bacteria are usually found in the 

 milk during the different seasons, for the reason that the 

 surroundings of the milk during its production and hand- 

 ling are not the same during different periods of the year. 

 As is natural, the greatest differences are found between 

 samples of milk taken when the cows were kept in the 



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