KXTHIiXAL onnAXS OF (1K.\ KiLlTIoX. 



35 



The teats of the Cow are fjenerally from two and a half to three and 

 a half inches in length, and, as has been said, this lenj^'th varies accord- 

 in"^ as the animal has reared a large or small number of calves. The 

 two anterior are generally the longest, and the corresponding (juarters 

 furnish more milk than the others. The dartoid tissue around the free 

 extremity of the teat, acting as a sphincter, prevents the passive escape 

 of the milk from the orifices of the excretory ducts; for if a small cannula, 

 scarcely larger than one of these ducts, be inserted slightly beyond the 

 orifice, the secretion immediately Hows. And when the end of a teat 

 has been wounded, or when the elastic tissue of this part has been divided 

 in the performance of some operation, there is no longer any obstacle to 

 the emission of the milk. 



The arteries that supply the mamm® of the Cow with blood are 

 derived from the external pudic. The branch of each side, on reaching 

 the lateral glands, divides into two principal trunks, one of which goes 

 to a corresponding quarter; that which is destined for the posterior 



B 



. o.;v 



«• 



Fifc-. 19. 



A. Lob'ile of the Mainniie filled with Milk ; 

 r.. Milk Globules ; C, Colostrum : a. Cell 

 with a \'ir<ible Nucleus; /*, Cells fmrn 

 which the Nucleus has disappeared. 



Fig. 20. 

 Skc-i'ion ok thk Cow's Te.\t. 

 o, ti. Principal Lactiferous Ducts ; 

 /;. Lactiferous Sinus ; r, r. Acini ; 

 (I, Klastic or iJartoid Tissue of 

 the Teat ; <\ Orifice of the Teat. 



gland beuds at a right angle backwards, the branch for the anterior 

 quarter — the largest — descending perpendicularly, to become subdivided 

 into numerous ramuscles and terminal twigs. The veins and nerves 

 are derived as in the Mare. 



In the Cow, the secretion of inilk can be excited and maintained by 

 regular " milking," the only suspension occurring before the birth of 

 another calf. 



Sheep ami Goat. 



In the Sheep and Goat there are only two mamnijc, as in the Mare 

 and Ass, though they are formed on the same plan as in the Cow. They 

 are also inguinal, somewhat hemispherical and voluminous, particularly 

 in the Goat, and each is provided with a single conical, well-detached 

 teat. The latter animal has sometimes, in addition, two posterior rudi- 

 mentary teats, and the galactophorous sinus of each ordinary teat is 

 very large, the walls of the teat being thin ; it is capable of containing, 

 in some instances, nearly three ounces of milk. 



