appreciates the evidence which now exists showing the remark- 

 able results which can be achieved, even in ordinary dairies by 

 the rank and file of dairy farmers, in the production of milk ot 

 the highest sanitary character. 



The first step in sanitary milk production must deal with the 

 dairv cow herself. The process of milk manufacture consists 

 in the transformation of the raw material, which is the food 

 consumed by the dairy cow, into the finished Prof^t-f^^ 

 milk This is done through the absorption into the blood ot the 

 cow of certain products supplied by the digestive organs. The 

 circulation of the blood carries these materials to the cows 

 udder and distributes them through all parts of the udder by 

 the subdivision of the arteries into a network of fine branches 

 The udder itself is an instrument called a gland, which is of such 

 a spongy texture that it is subdivided into numerous small 

 pockets or cavities, all of which empty into channels or canals 

 These pockets are lined with numerous cells, which are small 

 units of animal matter capable of abstracting from the blood 

 the materials necessary for the formation of milk, and discharg- 

 ing these into the milk canals. In the performance of this act 

 much of the animal matter lining the walls of these canals is 

 destroyed and broken off, so that in addition to the milk flow 

 itself there is a constant shedding of the tissues lining the 

 udder, composed of the finest particles of animal matter, which 

 flow away in the milk. Many of these consist of the white 

 blood cells which flow in the blood, and find their way through 

 the walls and canals into the milk. When the sediment from 

 the milk of a healthy cow is collected by the use of a centrifuge 

 such as a clarifier, under the microscope these cells which have 

 been shed from the walls of the udder can be plainly seen. 

 When the udder of a dairy cow is inflamed the appearance is 

 remarkably changed, showing these cells blurred and in the 

 process of destruction mixed with large numbers of bacteria 

 and often the bacteria can be seen clustered within the bodies 

 of some of the white blood cells, which are actually engaged 

 in their remarkable duty of devouring the bacteria of disease. 

 Such inflammation of the cow's udder is extremely common, 

 and can be found present in the majority of large dairy herds. 

 In producing sanitary milk the farmer must begin by the elimi- 



