THE DAIRY. 267 



breeds of the country in detail, it will be well to direct at- 

 tention to the subject of Milk and its products, as connected 

 with the economical value of breeds, and, in certain cases, 

 serving to distinguish them. 



THE DAIRY. 



MILK is the liquid food derived from the blood of mam- 

 miferous animals for the nourishment of their young. It is 

 secreted in glandular sacs termed mammae, the number and 

 disposition of which vary in different tribes of animals. Some- 

 times they consist of a single pair, as in the female of the 

 Horse, the Sheep, the Goat ; sometimes of more than one 

 pair connected together, as in the Cow ; and sometimes of 

 several pairs, extending along the lower part of the abdomen, 

 as in the Hog, the Dog, the Cat. These organs are filled 

 with innumerable glandular lobes, from the size of a millet- 

 seed upwards, through which the blood, circulating in myriads 

 of vessels finer than the finest hair, gives off the milky secre- 

 tion. From these lobes proceed little ducts or tubes, which, 

 gradually uniting, form larger ducts, and then reservoirs or 

 sinuses, which communicate with the papillae or nipples. The 

 milk is secreted at the birth of the young, and continues to 

 be supplied for a longer or shorter period, according to its 

 wants. It differs somewhat in its composition in different 

 species ; but in all of them it is a whitish liquid, opaque, and 

 of a slightly saccharine taste. It consists essentially of wa- 

 ter, holding in solution and suspension various substances, 

 some of which can be readily separated from the rest. Of 

 these the principal are, 1. An oily substance, which, from its 

 less density, rises to the surface, and, being agitated, forms 

 butter ; 2. An albuminous matter, which, by the action of 

 certain substances, coagulates, and forms curd or cheese ; 

 and, 3. A species of sugar, which can likewise be obtained 

 separately from the other constituents. 



