Every cow has more or less dirt on her sides and udder; some have a great deal. When the cow is milked, much of the dirt falls into the milk bucket. This dirt always contains a great many germs of different kinds, and many of them are germs that cause disease. Straining the milk will take out much of the dirt, but disease germs will go through the finest strainer that was ever made. In Figure 13 we see a man milking a dirty cow. The owner has allowed his lot to become so dirty that the cow cannot find a clean place in which to lie down. If the man kept his lot clean, and if before milking the light dirt on the cow's sides and udder were wiped off with a damp cloth, no germs would fall into the milk. [Sidenote: (_2_) By dirt in the cow barn] Another source of dirt and disease germs in milk is the barn. The walls of a barn where cows are milked should always be kept clean and should be whitewashed frequently. If this is done, there will be comparatively little dirt on the walls to fall into the milk. [Illustration: FIG. 14. Only clean milk will come from a dairy where proper precautions are taken.] Of course the walls and floors of a barn cannot be kept absolutely clean. There will always be some dirt, and the movements of the cows shifting their position and switching their tails, will stir up the dust; so it is important to remove the milk from the barn as soon as possible. Milk cans should never be kept in the barn. The milk should be taken directly from the barn to a cooling house and there strained. All barns where cows are kept should have plenty of windows, that there may be an abundance of light and fresh air. Cows need fresh air just as much as people do, while a barn that is not supplied with plenty of light is very likely to be a dirty barn. Keep dirt and disease germs out of the milk by keeping the barn clean and by taking the milk away from the barn as soon as possible. [Illustration: FIG. 15. A dirty, insanitary milk-house.] [Illustration: FIG. 16. A clean, inexpensive milk-house.] [Sidenote: (3) By dirt on the milkman] Another source of dirt and disease germs in milk is the milkman or milkmaid. No matter how careful we may be, our clothes hold more or less dust, and all dust contains germs, very often disease germs. When a person is milking a cow, the dust from his clothes is shaken off into the milk. The only way to avoid this is to wear, while milking, a special suit of clothes made of white cloth, which may be washed as soon as it shows the least particle of dirt. The milker's hands, too, are often dirty. Perhaps he carefully washes his hands after milking, but not before. It is a common custom for milkers to moisten their hands with milk while milking, and to do this frequently. The result is that dirty milk from their hands is constantly dropping into the milk pail. This is a very bad habit, and doubly bad if the milkman has not washed his hands before milking.