CLARIFICATION OF MILK. 



179 



Table VII. — Effect of Time and Temperature on Amount of Slime 

 Removed. 



[A single sample of commercial milk was used in this test.] 



1 High acidity. 



Discussion. — It is readily deducible from the above evidence that the 

 amount of slime differs widely when secured from the milk of the same 

 cow, from milk of different individual cows, and from mixed milks, whether 

 the mixed milks have the same origin or not. It is also manifest from the 

 work of this laboratory that samples from the same milk when clarified 

 under the same conditions yield practically the same amount of slime. 

 It follows, therefore, that the causes for these variations must be found in 

 the condition of the animal, the condition^, which surround the manipula- 

 tion of the milk, and the conditions which are involved in the clarification. 



From Lieutenant Davies' investigations it seems clear that with the 

 beginning of the period of lactation there is a great increase of slime. 

 This may be attributable to the colostral milk in which colostral cells are 

 numerous. Evidence also seems to point directly to inflammatory con- 

 ditions of the udder as a cause of increase; garget and other products of 

 inflammation and germ action within the udder are common, probably 

 much more so than is usuaUy recognized. As high as 20 per cent.- has 

 been given as the average appearance of garget in milch cows. This does 

 not seem unreasonable when one reflects on the sensitive nature of the 

 mammary gland, and the injuries to udders so frequently encountered by 

 milkers, giving rise to restricted or general mastitis. Doubtless the 

 variability in cell-content must influence the amount of slime to a con- 

 siderable extent. This may or may not be associated wdth inflammatory 

 processes. The so-caUed fibrin may be a variable quantity. These are 

 matters which we shall treat in greater detail later. 



Whether milk is dirty or clean, whether many micro-organisms are 

 present or not, whether it is fresh from the cow or has stood for some time, 

 whether it has been held at a low or high temperature, are all in some way 

 related to the variation in the amount of slime obtained. 



Again, the clarifier itself and the manner of manipulation have a de- 



' Ernst, W.: Milk Hygiene, translated by Mohler and Eichorn, p. 85. 



