=Removal of dirt after introduction.= The more primitive method of improving the quality of milk, so far as its dirt content is concerned, is to attempt to remove the grosser particles of contamination after entrance. In the case of straining, the method is usually applied at the time of milking, but in the case of filtering and clarifying, it is carried out at the milk station, in an effort to improve the appearance of milk and overcome the influence of careless methods of the producer. By the use of strainers, either metallic or cloth, it is possible to remove particles of hair, undissolved dirt and manure, but it must be remembered that these grosser _visible_ particles of pollution are not really the cause of the troubles which may ensue in improperly handled milk. The bacteria which are adherent to these foreign particles are in large measure washed off in the process of straining, and pass through the meshes of the finest strainer. The main service, therefore, of straining is to improve the appearance of the milk, and it has no effect on the quality in any way. =Production of clean milk.= The problem of clean milk is important, whatever may be the use to which milk may be put. It is important in the manufacture of butter, but owing to the fact that the fat is not readily acted upon by bacteria, it is not so sensitive to bacterial conditions, as when the milk is made into cheese. In this product, the bacterial condition of the milk is a matter of prime importance. In milk destined for direct consumption, the exclusion of the bacteria becomes yet more important. While it is impossible to exclude bacteria so completely that milk will not undergo fermentative changes, yet for domestic consumption it is preferable to have milk with as low bacterial content as can readily be secured. The highest type of market milk, that known as sanitary, or certified, is produced under such extreme conditions of care as to contain the minimum germ content. To accomplish these results requires such stringent control as to increase greatly the cost of the product. Pure, clean milk can be produced at a very slight increase in cost over the regular expense of milk production, if the right kind of attention is given to certain details of a practical character. Improvement in our milk supplies must largely come from this source, for any improvement to be permanent must be made to pay, and it requires considerable education to secure the co-operation of consumers and their willingness to pay for any material increase in the quality of the product.