io MILK AND THE PUBLIC HEALTH CHAP. 



Delepine points out that there is a lymph gland at 

 the posterior end of each half of the udder, close to its 

 attachment to the abdominal wall and to the inner aspect 

 of the thigh. These glands are soft and difficult to recognise 

 by palpation when they are normal, but when diseased they 

 often reach a large size and may then be felt through the 

 skin. When the udder is tuberculous this mammary lymphatic 

 gland is generally considerably enlarged and tuberculous. 



The mammary gland in the cow, like the human organ, 

 is composed of a number of lobules united by fibrous tissue. 



FIG. 1. Cow's Udder stripped of its Skin to show A, a section of one of the four milk cisterns 

 into which a tube (a) has been passed through the teat ; B, smaller milk sinuses 

 around A ; C, mammary vein ; D, origin of the superficial abdominal vein or " milk 

 vein." 



The lobules are composed of acini. The milk is secreted by 

 the cells of the acini and passes into the small lactiferous 

 ducts. These unite to form the galactopherous canals from 

 which the milk passes into the milk cistern or galactopherous 

 sinus. The milk cistern receives the milk of all the acini 

 of one quarter, and the fluid passes from this to the exterior 

 by means of the teat canal. The teat canal gradually narrows 

 to its termination at the end of the teat. The teat walls 

 are thick and contain elastic tissue circularly disposed, which 

 at the orifice acts as a sphincter, preventing the passive escape 

 of the milk. 



In the intervals between milking, the milk collects in 



