RULES AND REASONS FOR FARM CARE OF MILK. 99 



germ life. Fig. 4 shows a culture made of several hairs that were allowed 

 to fall on a sterile gelatine surface. When the animal is shedding her 

 hair, there is nothing to prevent the falling of these germ-laden particles 

 directly into the milk. Even where the hair is not rubbed off, the move- 

 ments of the animal and milker are constantly dislodging particles of fine 

 dust that settle in a continuous shower into the warm nutrient fluid be- 

 low. It may be thought that straining the milk removes this source of 

 filth. So it does the visible filth, but not until the invisible living germ 

 life has been washed off, into the fluid, there to set up the various fermenta- 

 tions that it is capable of producing. The kind of organisms that gain 

 access to the milk from this source is, generally speaking, thoroughly un- 

 desirable. They are largely fecal bacteria, derived from decomposing 

 animal excreta. In a large number of instances they are spore-bearing 



FIG. 4. Showing the bacterial contamination arising from hair. These three hairs were allowed 

 to fall on a sterile gelatine surface. The adherent bacteria developed readily in this medium 

 and the number of bacteria thus introduced into the milk from these hairs can be estimated 

 by the developing colonies that show as irregular protuberances along the line of the hair. 



bacteria that are very resistant, and the type of fermentative activity that 

 they are capable of producing in milk is undesirable in cheese making. 



Besides the dirt and filth that is derived directly from the animal, 

 matter from other sources may gain access to the milk by being carried 

 in the hairy coat of the animal. 



Cows wading in stagnant water in midsummer often cover their bag 

 and flanks with slimy deposits that dry on and in this condition particles 

 of dust are readily dislodged. 



The custom of leaving the milk in the barn even during the milking 

 is a practice that should be thoroughly condemned. Not only can it absorb, 

 to a certain extent, the odors peculiar to the place a point which will 



