416 MANUAL OF CATTLE-FEEDIKG, 



of tlie lobes cut obliquely ; d is the teat ; e tbe milk- 

 cistern, into wliicli all the lobes empty; and /the outlet of 

 the teat. 



The vesicles above described are covered with a net-work 

 of iine blood and lymph vessels, both of which are very 

 fully developed in the udder. Each lialf of the udder has 

 usually two, more seldom three, teats. 



Formation of the Milk. — The space in the vesicles of 

 the milk-gland contains originally only a small quantity of 

 a yellowish mucus, but when conception takes place the 

 cells begin to enlarge and to fill with fat-globules. At the 

 same tune new cells are formed, and the old ones are 

 pushed forward and fill the vesicle, and, toward the end of 

 pregnancy, even reach the large milk-ducts and the milk- 

 cistern, partly separating from each other in the process. 

 Wlien birth takes place the cell-building in the vesicles 

 becomes more rapid, and is somewhat altered in character. 

 The previous secretions are the first to appear, foi-ming the 

 colostrum, which is followed in three or four days by the 

 true milk. 



The colostrum is a thick, yellowish fluid, rich in albumin 

 and salts, but containing little casein, and characterized by 

 the presence of round bodies, which are simply whole cells 

 from the interior of the vesicles. The colostrum contains 

 also a large number of the milk-globules shortly to be 

 described. 



In the production of the true milk, which soon follows 

 the colostrum, a rapid formation of new cells takes place 

 in the vesicles, these cells become completely filled with 

 fat-globules, and then break up entirely, setting free these 

 globules, which float in the fluid which is secreted at the 

 same time, and form milk-globules. This process takes 

 place much more rapidly than in the case of the colostrum. 



