58 ANATOMY AND PHYSIOLOGY. 



water, with sugar, salt, albumen and whatever may he in solution 

 in the water. 



Colostrum is a f.uid which accumulates in udder during the 

 latter part of pregnancy and differs from milk in containing 

 the colostrum cells, a few oil glolniles. much albumen and but 

 little casein, fat or sugar. It has mild cathartic effect on the 

 young animals. 



The quantity and quality of the milk depends on several fac- 

 tors : food, period of lactation, period of gestation, condition of 

 the nervous system, quantity of blood passing through the udder, 

 amount of water in the food, individual peculiarity or hereditary 

 tendency. Breed would naturally be included under the latter. 



FIG. 26. ONE QUARTER AND 

 TEAT OF COW'S UDDER. 



(O. K. C.) 

 C. Milk Cistern. Note constric- 

 tion just below the cistern. Anoth- 

 er constriction at end of teat. Holes, 

 shown in the gland above, are milk 

 ducts cut across. 



FIG. 27. MILK VESICLES AND 

 OUTLET DUCTS. MAGNIFIED. 



Blood supply. — The mammary glands receive their supply 

 through the mammary artery, which distributes branches through 

 the two glands in each half of the udder, one artery on each 

 side. The blood for one-half the udder thus comes through the 

 external iliac artery, then through a branch of that, the pre- 

 pubic, and then through a branch of the prepubic, the external 

 pudic. 



The mamiuary artery is one of the terminal branches of the 

 external pucHc. When the cow stands still more blood flows 

 through the udder than when she is exercising. The large vein 

 which may be felt in front of the udder on each side and called 

 by dairymen the "milk vein" is properly the subcutaneous ab- 

 dominal vein. It docs not drain the udder as popularly sup- 

 posed. 



