278 URINARY SYSTEM. 



and is constantly besmeared within with a mucous secretion, to 

 shield it from the acrimony of the urine. 



Organization. — T/ie emu/gent arteries, right and left, arise 

 immediately in front of their respective glands from the sides of 

 the posterior aorta: each enters the notch, and there divides into 

 three, or four, or even five principal branches, which, unlike the 

 trunk, become flexuous in their course and then penetrate the 

 glandular substance : the outer branches turning in contrary 

 directions, one forward the other backward, to enter the cortical 

 part at once ; those in the middle traversing the tubular to ar- 

 rive at it ; in which they all subdivide and ramify to terminate 

 as afoie described. 



T/ie emu/gent veins, which exceed in volume, though not or- 

 dinarily in number, the arteries, correspond in their ramification 

 to those vessels : their terminating branches, three, four, five, or 

 upwards in number, converging within the notch, there unite into 

 one trunk, which accompanies its artery and ends in the posterior 

 vena cava. 



The nerves supplying the kidney are derived principally from 

 the renal plexus, and very numerous they are : notwithstanding 

 their numbers, however, and notwithstanding the acute pain 

 which accompanies active inflammation in it, the organ in the 

 liealthy condition is by no means remarkable for its sensibility. 



OF THE CAPSULyE RENALES. 



These are two small, elongated, irregularly-formed, brownish 

 bodies, a right and a left, placed opposite to the kidneys, be- 

 tween those glands and the spine. The right, the longer one, 

 lies in contact with the posterior vena cava, and reaches forward 

 to the liver ; the left, the broader one, and rather obliquely 

 placed, is opposed to the aorta ; and, anteriorly, is contiguous to 

 the pancreas : they are respectively connected to these several 

 parts by loose enveloping cellular substance, and are furthermore 

 retained in their places by the peritoneum, which covers their 

 under surfaces. Their magnitude varies with age : in early fce- 

 tality they are equal in volume to the kidneys themselves; their 

 subsequent growth, however, being less rapid than that of the 

 kidneys, this equality in the course of time becomes destroyed. 

 Their outward borders are partially cleft by several little notches, 

 giving them a lobulated appearance. They possess tunics of 

 their own of condensed cellular tissue, processes from which 

 penetrate their substance and enter into their composition. 



Structure. — Divided by a perpendicular section, the renal 

 capsule shews a palish brown substance above and below, in- 



