106 BACTERIOLOGY. 



clean hands, and clean milk-pails. Immediately after 

 the milk is drawn, it should be cooled to 5 C. (40 F.) 

 and kept at this temperature until sold. 



P Stion" On account of the difficulty in maintaining strict 



supervision over the milk-supply in cities where the 

 milk is collected from a wide area, we have come to 

 the conclusion that pasteurization is essential to render 

 the supply safe for use, particularly in infant feeding. 

 Pasteurization is accomplished by heating the milk to 

 60 C. (140 F.) for twenty minutes or 65 C. 

 (158 F.) for fifteen minutes. The milk is imme- 

 diately cooled to 5 C. (40 F.) and kept at this tem- 

 perature till used. Milk to be used in feeding infants 

 should be modified and poured into the nursing bottles 

 before being pasteurized. It should be used within 

 twenty-four hours. The pasteurization kills all the 

 bacteria, but not the spores. If the milk is cooled as 

 directed, the spores will not develop. 



The bacteria usually present in milk are harmless 

 in so far as they are able to produce specific disease; 

 but while they may be considered as harmless for 

 healthy adults, they may be very dangerous for in- 

 fants and sick persons. The great loss of life among 

 infants under 2 years of age from intestinal or diar- 

 rheal diseases show this. During the summer months, 

 when the number o-f bacteria is more than at any other 

 time of the year, the milk undergoes chemical changes 

 which lead to disturbances in digestion and infection of 

 the intestines. 



Diseases other than these caused by the ordinary 



