80 THE MILK QUESTION 



sample will be found crowded with long chains. Often 

 streptococci, if present, are in the form of diplococci, or 

 very short chains. The common interpretation is to regard 

 the short-chained varieties and the very large streptococci 

 as probably harmless, while the long chains (six elements 

 or more) are looked upon with suspicion, and may be 

 taken as an evidence of inflammatory conditions of the 

 udder. A milk containing a large number of streptococci 

 is certainly not a safe article of diet. 



Unfortunately the most virulent streptococci, that is, 

 the ones that are most to be dreaded, are the very forms 

 that grow poorest upon our artificial culture media. Thus 

 the routine examination of the Deerfoot Farm milk, dur- 

 ing the epidemic of sore throat which occurred in Boston 

 in 1911, failed to discover streptococci. The disease pro- 

 duced, however, was a streptococcal infection. 



Leucocytes in milk 



A large number of cells are normally present in cow's 

 milk and probably in the milk of all other animals. These 

 are not to be regarded as the result of inflammation unless 

 true leucocytes or pus cells are excessive or accompanied 

 by streptococci. The cells in normal milk are, for the most 

 part, probably degenerated epithelial cells, although they 

 are commonly called leucocytes. 



The cells present in milk, 1 the so-called leucocytes, are 

 very diverse in nature, and when critically examined the 

 majority distinctly differ from leucocytes. The cells ordin- 

 arily present in normal milk, however fresh, practically 

 never exhibit amoeboid motion. The ingestion of bacteria 

 by the cells in milk is practically absent. 



The number of cells in milk is greatly increased in the 

 presence of garget, toward the end of lactation, on ap- 

 proaching calving-time, during periods of excitement, or 

 they may be increased on account of various other factors. 

 1 For a discussion of the cells in milk see pages 28-30. 



