vi] THE BACTERIA OF MILK 81 



Uhl in different cities showed from 3,338,775 to 

 55,365,800 per litre (If pints). Their number 

 rapidly increases on keeping, and it has been 

 estimated that in milk which has stood six hours 

 there may be from two to six millions, on an 

 average, in one cubic centimetre. The tempera- 

 ture, of course, will affect their number. Conn 

 has found, for example, that in a sample of milk 

 kept for four days in- a cold cupboard there were 

 only 10,000 bacteria per cubic centimetre ; while the 

 same milk, taken from the cupboard and left in a 

 warm room for six hours, contained 1,000,000. The 

 following table shows the influence of temperature 

 on their rate of increase : 



INCREASE IN NUMBER OF BACTERIA (CNOPF). 



In 1 hour 

 ,, 2 hours 



55 55 



A 



55 ^ 5) 



As further illustrating the influence of tempera- 

 ture, it may be mentioned that a difference of 10 C. 

 (18 Fahr., viz. from 59 to 77 Fahr.) made a differ- 

 ence in milk kept for 15 hours of 71,900,000 (viz. 

 from 100,000 to 72,000,000) bacteria per cubic centi- 

 metre (Miquel). In milk kept for 24 hours at 25 C. 



6 



