38 Veterinary Obstetrics 



discharge of milk from the udder, or, when the young is sucking 

 one teat, milk flows freely from the others or, even, when a milk- 

 man is drawing milk from one cow, a neighboring one has an in- 

 voluntary discharge of milk. 



Under the influence of anger, fear or other disturbances, the 

 flow of milk, in the process of milking, abruptly ceases, the ani- 

 mal " holds up" her milk and it cannot be withdrawn. 



One milker can abstract from an udder a greater amount of 

 milk than another, yet each will withdraw with equal care all 

 the milk which reaches the teat. The flow of milk is not directly 

 subject to the control of the lactating animal, but involuntary on 

 her part, subject to external in:§uences over which she exerts 

 but very imperfect power. 



In the mare, there are two hemispherical mammae, flattened 

 from side to side, situated in the inguinal region and each closely 

 attached in the region of the external abdominal ring, through 

 which their chief vessels and nerves pass. 



There are two or more milk cisterns in each gland, from which 

 corresponding excretory ducts pass to the apex of the teats to 

 escape by separate orifices ranged one behind the other in the 

 broad, antero-posteriorly flattened nipple. 



In ruminants, the mammae are also inguinal. In the cow, the 

 right and left halves of the udder are quite distinct from each 

 other although lying in contact, their fibro-elastic envelopes being 

 completely separated by areolar tissue. Each lateral half is 

 divided into two intimately connected "quarters," an anterior 

 and posterior, with separate excretory ducts and teats. 



Each quarter has but one milk cistern, and this is of great size, 

 into which all lacteal sinuses lead and froni which a single excre- 

 tory duct opens through the apex of the teat to the exterior. 



There are generally one or two rudimentary glands with teats 

 behind the posterior quarter, which frequently function very 

 slightly immediately after calving, while, in some cases, thev , 

 secrete a noticeable amount of milk. In one cow observed by the 

 author each lateral half of the udder consisted of a single gland 

 or "quarter" with but one teat like that of the ewe or goat. 



In the bitch and cat there are eight to ten mammae and, in the 

 sow, ten to twelve. In the mammas of the .sow there are two or 

 more small milk cisterns to each gland, each of which opens at 

 the apex of the teat by a separate orifice. The mammae of car- 



