STRUCTURE OF KIDNEYS. 



527 



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and by a portion of the small intestines. The anterior surface of 

 the kidney is convex, while the posterior is flat ; the superior ex- 

 tremity is in relation with the supra-renal capsule ; the convex 

 border is turned outwards towards the parietes of the abdomen ; 

 and the concave border looks inwards towards the vertebral column, 

 and is excavated by a deep fissure the hilus renalis in which are 

 situated the vessels and nerves and pelvis of the kidney ; the renal 

 vein being the most anterior, next the renal artery, and lastly the 

 pelvis. 



The kidney is dense and fragile in tex- 

 ture, and is invested by a proper fibrous 

 capsule, which is easily torn from its sur- 

 face. When divided by a longitudinal in- 

 cision carried from the convex to the con- 

 cave border, it presents in its interior two 

 structures, an external or vascular (corti- 

 cal), and an internal or tubular (medullary) 

 substance. The tubular portion is formed 

 of pale reddish-coloured conical bodies cor- 

 responding by their bases with the vascular 

 structure, and by their apices with the hilus 

 of the organ; these bodies are named cones, 

 and are from eight to fifteen in number. 

 The vascular portion is composed of blood- 

 vessels, and of the plexiform convolutions 

 of uriniferous tubuli, and not only forms 

 the surface of the kidney, but dips between the cones and surrounds 

 them nearly to their apices. The tubuli uriniferi communicate fre- 

 quently with each other in the vascular structure of the kidney, and 

 terminate in anastomosing loops and cascal extremities. They are 

 each surrounded by a fine network of capillary vessels. When 

 examined with a lens of low power, a multitude of small globular 

 bodies, glomeruli (corpora Malpighiana) are seen to be interspersed 

 through the vascular structure of the organ, and to be connected to 

 the minute twigs of the arteries. They are about -f^th of an inch 

 in diameter, are composed of an aggregated plexus of capillary 

 vessels, and enclose a small central cavity, the use of which is as 

 yet unknown. 



The Cones are composed of minute straight tubuli uriniferi of 

 about the diameter of a fine hair; they divide into parallel branches 

 in their course, and commence by minute openings upon the apex 

 or papilla of each cone. The papillae are invested by mucous mem- 



* A section of the kidney, surmounted by the supra-renal capsule ; the swellings 

 upon the surface mark the original constitution of the organ by distinct lobes. 1. The 

 supra-renal capsule. 2. The vascular portion of the kidney. 3,3. Its tubular portion, 

 consisting of cones. 4, 4. Two of the papillre projecting into thin corresponding 

 calices. 5, 5, 5. The three infundibuli ; the middle 5 is situated in the mouth of a 

 calyx. 6. The pelvis. 7. The ureter. 



