igO AGRICULTURE OF MAINE. 



BACTERIA CONTENT AS A FACTOR IN DETERMIN- 

 ING THE MARKET VALUE AND HEALTHFULNESS 

 OF MILK. 



Hermann C. Lythgoe, Director, Division of Foods and Drugs, 



Massachusetts State Department of Health. 



Bacteria are microscopic plants which reproduce themselves 

 by splitting up into two or more bacteria, if they are provided 

 with suitable food. Milk at the point of secretion in the mam- 

 mary glands is sterile — that is to say, it contains no bacteria, 

 but it always contains bacteria when drawn, even if this is done 

 under the most careful conditions. The greater number of bac- 

 teria in milk are obtained from the hands and clothing of the 

 milker, from the dirt, hairs, etc., falling from the cows into the 

 milk, and from the dirty utensils with which the milk may come 

 in contact. If the udder of the cow is diseased, bacteria are 

 liable to invade the milk and, in some instances, these bacteria 

 are capable of producing severe sickness among people who 

 drink the milk. Milk is an ideal food for bacteria, as well as 

 for men and animals, and the growth of bacteria causes certain 

 chemical changes to take place in the milk, of which souring 

 is an example. In general, the chemical changes taking place in 

 milk, due to the growth of bacteria, are harmless, but, occa- 

 sionally, very poisonous by-products of fermentation can be 

 produced. This is a very unusual occurrence, fortunately, for 

 when it does occur the milk gives no indication of its nature 

 by sight, odor, or taste. It is desirable to keep out of the milk 

 as many bacteria as possible, and to stop the growth of those 

 which may get into the milk, by keeping down the tempeiulure. 

 Like most plants these bacteria grow be.it in a warm climate 

 and do not enjoy the frosts. If the milk from a diseased udder, 

 or milk contaminated with the bacillus of typhoid fever or with 

 disease germs which may grow in milk, is mixed with other 



