346 BOARD OF AGRICULTURE. [Pub. Doc. 



MILK AND CREAM. 



BY J. B. LINDSEY, PH.D., DEPARTMENT OF FOODS AND FEEDING, HATCH 

 EXPERIMENT STATION OF THE MASSACHUSETTS AGRICULTURAL 

 COLLEGE. 



General Structure of the Udder of the Cow. 



The udder of the cow consists of two milk glands, a left 

 and right, separated from each other by a fibrous tissue 

 (ligamentum suspensorium mammarum). This tissue layer, 

 or wall of division, is connected by elastic muscles with the 

 connective tissue which surrounds the glands, and also with 

 the muscles of the belly, thus holding the milk glands in 

 position. 



The two milk glands are each of a reddish-gray color, and 

 consist, properly speaking, of a glandular structure known 

 as the gland basket. In case of ordinary mature milch cows, 

 each gland is about 6 to 12 inches in depth and 9 to 20 inches 

 in length. The glandular mass may be divided into lobes, 

 lobules and alveoli. Plumb makes this clear by likening the 

 lobe to a bunch of grapes, the lobules to a single grape and 

 the alveoli to smaller divisions within the single grape. The 

 lobules of the gland are surrounded by a fully developed net- 

 work of capillary vessels, in which the materials for the 

 formation of the milk circulate through the numerous lymph 

 tracts. The alveoli are microscopic terminations of ex- 

 tremely fine canals. They are covered externally with a 

 structureless membrane, and internally are lined with a con- 

 tinuous single layer of epithelial cells. These cells have a 

 diameter of .04 of a millimeter. When the cow is in milk 

 they are swollen and protrude into the alveolian cavity. 

 The microscopic canals, of which the alveoli are the enlarge- 

 ments, unite together among themselves into ever-widening 

 ducts, — the milk ducts, — and end eventually in large, hol- 

 low cavities, the so-called milk cisterns or reservoirs. 



