THE DISEASES OF CATTLE. 203 



arteries ; they accompany the latter, and finally converge into 

 one trunk and terminate in the posterior vena cava. The 

 nerves of the kidneys are derived from the renal plexus. 



THE URETERS. 



Each kidney is connected with the bladder by a common 

 dact or tube, known as the ureter; these ducts are much 

 stronger and larger than those found in the horse ; they are 

 composed of two tunics, the external one is both fibrous and 

 muscular in a longitudinal direction, which permits it to con- 

 tract and extend in exact ratio as the bladder contracts when 

 empty and expands when filled. The internal membrane is of 

 mucous texture, and is constantly lubricated with a mucous se- 

 cretion which defends it against the irritating qualities of the 

 urine. 



THE BLADDER. 



The bladder of an ox is much larger than that of the horse ; 

 it is a musculo-membranous sac, or bag, and is located within 

 the pelvis, bounded above by the rectum, and below by the 

 internal surface of the pubic bones. In the cow we find the 

 bladder located between the rectum and the uterine organs. 

 The bladder has a transverse ligament inserted into the lateral 

 parts of the pelvis ; it has three coats ; one is derived from the 

 peritoneum, or lining membrane of the abdominal cavity — 

 which gives the bladder an external covering — the middle 

 coat of the bladder is composed of muscular fibres, which run 

 in longitudinal and circular directions. The internal mem- 

 brane or coat is more highly organized than the others ; it is 

 furnished with excretory outlets, from which issues a mucous 

 secref^ i for its own protection. The bladder is divided into 

 fundus, body, and cervix. The fundus is that prominent part 

 which faces anteriorly or towards the intestines, and when the 

 bladder is full of urine, it protrudes into the abdominal cavity. 

 The body is the bulky or capacious part generally more rounded 

 when full, than in the horse's bladder. The cervix is the neck 

 or contracted part of the bladder ; it is surrounded by muscu- 



