440 THE DAIRYMAN*S MANUAL. 



central mass ; this is shown at figure 104, in which the 

 gland vesicles are highly magnified. These gland cells 

 become infiltrated with fat during the period of milk 

 production, and this fat supplies the cream of the milk. 

 The milk ducts converge and run into two, three, and 

 sometimes four large channels, which in their turn empty 

 into a larger reservoir situated at the base of the teat. 

 These milk ducts are lined with a fine mucous mem- 

 brane, and this itself secretes some portion of the milk 

 w^hich always contains more or less mucus. The teat 

 is formed of, first, this fine mucous membrane, which is 

 very delicate and sensitive, then a thick layer of tissue 

 over which the mucous membrane is doubled, and this 

 tissue is again covered by the skin. Among this tissue 

 are numerous bundles (fasciculi) of muscular fiber, ar- 

 ranged in a circular and a longitudinal manner around 

 the duct or orifice of the teat. At the base of the teat is 

 the sphincter muscle, which operates as an elastic band 

 or ring to close the duct ; below this are several other 

 bands of concentric muscular fiber, and around the duct, 

 lengthwise of the teat, are arranged numerous other 

 fibers. The whole of the structure of the glands is sup- 

 plied abundantly with nerves. 



From this description of the milk glands and the fur- 

 ther account of the functions and character of the ulti- 

 mate cells of the gland vesicles or lobules given in a 

 previous chapter, their delicate and sensitive nature can 

 be readily understood. The large supply of blood which 

 passes through the glandular substance from the impor- 

 tant artery which supplies the whole reproductive system, 

 renders it remarkably sensitive to any disturbances of the 

 circulation, or any accidental local derangement. In- 

 flammation arising from excessive circulation and supply 

 of blood is accompanied by engorgement of the fine 

 capillary vessels and blood may then pass directly into 

 the secretory glands, and thence with the cell matter into 



