THE URINARY APPARATUS. 581 



fissures, may be recognized. The ileo-lumbar portion— so named because of its constant 

 position in this region— is the most advanced; it is often the largest. Tlie middle is the 

 narrowest ; it is turned towards the ileo-sacral region, to enter the pelvis. The posterior is 

 contained in that cavity, and is again larger. These two latter portions are designated as the 

 anterior or superior pelvic, and the inferior or deep pelvic portions. Their internal and 

 superior border is often notched by a series of transverse fissures, produced by the protrusion 

 of the transverse processes of the sacral vert-^bras, as the lungs are furrowed by the projection 

 of the ribs." ' 



The excretory apparatus is incomplete, and is only formed by the ureters, which open into 

 the cloaca, where tlie urine is mixed with the fseces. Only one bird— the Ostrich— possesses 

 a bladder, which is disposed in a particular manner. 



Comparison of the Urinary Apparatus of Man with that op Animals. 



1. Kidneys. — The two kidneys of Man have, like those of tiie smaller domesticated animals, 

 the same shape — that of a haricot bean. The average weight is about from three to five ounces. 

 Contrary to what is observed in the Horse, the left kidney is more voluminous tiian the right, 

 and is higher. 



The kidneys are simple externally, thougli their tissue is disposed in distinct lobes, which 

 number from eight to fifteen, and each is composed of a Malpighian pyramid and a superposed 

 pyramid of Ferrein ; they terminate, towards the hilus, by a cone or renal papilla, each 

 surrounded by a calyx, and are separated by small prolongations of the cortical substance — 

 the columnx Bertini. 



2. Ureters. — These canals are disposed at their origin as in the Ox : they terminate as in the 

 other animals. In the hilus of the kidney are from eight to fifteen prolongations or calices, 

 ■which unite into a larger cavity or great calyx, tliat finally opens into the renal pelvis ; this is 

 immediately followed by the ureter. 



3. Bladder. — The large extremity of this organ is directed downwards in the bottom of the 

 pelvis, where it is continuous with the urethral can il ; its summit is directed upwards, and is 

 frequently pointed. Its mode of attachment and internal conformation are the same as in 

 animals ; and, as in the Horse, the peritoneum envelops it very incompletely. The muscular 

 fibres are arranged in three planes — -a superficial, which forms a band that is carried from 

 the anterior to the posterior face in passing over the summit ; a middle plane, the fibres of 

 which are circular; and a deep plane witii reticulated fibres. 



Supra-renal capsules. — This name is quite appropriate to these bodies, as in Man — or at 

 least in the foetus — they form a kind of helmet that covers the upper part of the kidney. 

 There is nothing to add respecting their structure. 



' Cuvier, Anatomie Compar^e, 2ud Edition. Paris : 1836-46. 



