176 BACTERIOLOGY FOR NURSES 



is extremely common , and at the same time it fur- 

 nishes one of the most favorable media for the growth 

 and multiplication of bacteria of all kinds. 



Many large cities have established a system of 

 milk inspection which rejects milk containing over a 

 certain number of bacteria, thus recognizing that 

 milk is one of the most important articles of food in 

 common use. 



Typhoid fever, diphtheria, scarlet fever, tubercu- 

 losis, and infantile diarrhoeas and gastric disorders 

 are largely disseminated by means of impure milk. 



Cleanliness is the most important measure used for 

 controlling the infection of milk; while " Pasteuriz- 

 ing" by heating to 60 C. (140 F.) for twenty 

 minutes will destroy any ordinary bacteria which 

 milk may contain. 



The action of all bacteria upon food materials is 

 not however to its detriment; in many articles of 

 food, such as butter, cheese, and other milk products, 

 vinegars, wines, etc., the activities of certain bacteria 

 are necessary for their flavor or aroma. 



In several industries, as the tanning of hides for 

 leather, and in the preparation of flax for linen, bac- 

 terial activity forms an important part of the process, 



