Practical dairy bacteriology, prepared for the use of students, dairymen, and all interested in the problems of the relation of milk to public health . any estimationof such particles as are too small to separate out by sedimentingor centrifugalizing, and they give no indication of the portionof the dirt that may have been dissolved in the milk. The ab-solute amount of dirt found is of no special significance, but ifnumerous estimations are made by the same individual on aseries of milk samples, the relative amounts will indicate therelative cleanliness of the different samples. Estimates made
Practical dairy bacteriology, prepared for the use of students, dairymen, and all interested in the problems of the relation of milk to public health . any estimationof such particles as are too small to separate out by sedimentingor centrifugalizing, and they give no indication of the portionof the dirt that may have been dissolved in the milk. The ab-solute amount of dirt found is of no special significance, but ifnumerous estimations are made by the same individual on aseries of milk samples, the relative amounts will indicate therelative cleanliness of the different samples. Estimates made 72 PRACTICAL DAIRY BACTERIOLOGY by different observers do not agree very closely because ofslight differences in technique. Figure 35 shows the amountof dirt collected under the udder of a cow during milking, bothwith, b, and without, a, previous washing of the udder. Theamount is cfertainly sufficient to emphasize the importance ofthis source of bacterial contamination. The determination of the amount of dirt in milk certainlygives a gauge as to the care exercised in its production. Butwhether such dirt determination can be of any value in the. FIG. 35—^RELATIVE AMOUNT OF DIRT FALLING FROM THE UDDER DURING MILKING, UNDER DIFFERENT CONDITIONSA. Udder muddy. B. Udder slightly soiled. One-half natural size. (Fraser) municipal testing of milk is somewhat questionable. It is notyet possible to give any standard as to the amount of dirt thatmay be allowed in passable milk, and there seems to be noreason for believing that the dirt determination will be adoptedas one of the methods of municipal examination of market milk is allowed to stand for several hours in a glass jar untilthe dirt settles at the bottom, an examination with the nakedeye will give the relative amount of dirt, and the results willprobably be as valuable as the longer laboratory methods ofdetermining the quantity, especially when it is remembered thatthe amount of dirt thus obtained varies quite widely w
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Keywords: ., bookcentury1900, bookdecade1900, bookidcu319, booksubjectdairying
