436 



PHYSIOLOGY. 



rior of the pelvis, before subdividing and entering the parenchyma of 

 the organ. 



The parenchyma is seen to be composed of two portions, an 

 external., investing cortical portion, and an inner medullary, or pyra- 

 midal, portion. 



The cortex is light brown in color, granular, and very friable. 

 The granular aspect is due to the presence of Malpighian corpuscles, 

 which are separated at regular distances by medullary rays, or striae, 

 which give to the cortex a radiate appearance. The boundary zone 

 is darker, and also striated from blood-vessels and uriniferous tubules. 

 It is through this portion that arteries and nerves enter and veins 

 and lymphatics pass from the kidney. 



Fig. 164. (LANDOIS.) 



II. Bowman's capsule and glomerulus. a, Vas afferens. c, Vas efferens. 

 fc, Endothelium of the capsule, c, Capillary network of the cortex, h, Origin 

 of a convoluted tubule. 



III. "Rodded cells" from a convoluted tubule. 2, Seen from the side, with 

 g, inner granular zone. 1, Seen from the surface. 



IV. Cells lining Henle's looped tubule. 



V. Cells of a collecting tube. 



VI. Section of an excretory tube. 



The medulla is composed of from eight to twelve pyramids, or 

 cones, of pale-red, striated tissue, known as the pyramids of Mal- 

 piglii; their number depends upon the number of lobes composing 

 the organ during the foetal state. It is the apices of these cones 

 which dip down into the calyces of the pelvis. 



Minute Anatomy. The kidneys consist of numerous tubular 

 glands intimately united together. The tubes, known as tubuli uri~ 

 niferi, take their origin in the labyrinth of the cortex as distinct 

 globular dilatations, each of which is known as Bowman's capsule. 



