BACTERIOLOGY OF MILK 221 



The Budcie process involves the addition of hydrogen 

 peroxide, and the heating of the milk for three hours to 

 52 to 53 C. Meat extract removes the peculiar taste 

 left by the treatment. In Behring's method 1 ounce of 

 perhydrol is added to 6 gallons of milk, and the milk 

 is then heated to 122 F. Behring believes that milk 

 loses some of its best qualities when exposed to daylight. 

 He advocates green or red milk-bottles. 



In the summer months it is a common practice to run 

 the milk as soon as possible through a cooler, which serves 

 to delay bacterial development. One of Houston's 

 ' counsels of perfection ' is the cooling to, and maintaining 

 at, a temperature of 10 C. of the milk. The standard of 

 the Academy of Medicine of Toronto requires the milk to 

 have been cooled to 45 F. within half an hour after milk- 

 ing, and kept at a temperature not exceeding this till 

 delivered. They also impose an age limit of twenty-four 

 hours. ' 



Bacteriological Examination of Milk. 



Sediment. This examination is carried out, not only 

 as a qualitative test, but also to obtain an idea of the 

 number of leucocytes present. It may safely be said that 

 no one can differentiate between a pus cell and a leuco- 

 cyte in a milk sediment, and it is only when the cells 

 occur in excessive numbers, or accompanied by pyogenic 

 organisms, that pus can be certified as present. At the 

 same time, it must be remembered that Revis and others 

 have shown that a very large leucocyte count can be 

 obtained from the milk of healthy cows. Uncertainty 

 exists as to the significance to be attached to the relative 

 numbers of leucocytes and streptococci. Savage (Journal 

 of Hygiene, April, 1906) has shown the absence of any 

 relationship between these in the milk of healthy cows; 

 but he also calls attention to the fact that the number 

 of pus cells present in milk from inflamed udders would 

 be much higher than in the milks he examined. 



A number of different processes for estimating leuco- 

 cytes, allowing varying degrees of inaccuracy, are in use, 

 with the consequence that the data have little significance 

 to anyone except the operator. Savage (ibid.) dilutes 

 the milk with Toisson's fluid, and, after centrifuging, 

 counts the leucocytes in the Thonia-Zeiss counting 



