HO LABORATORY METHODS OF 



the calyces of the kidney. It will be remembered that 

 the uriniferous tubules are gathered into bundles and 

 then proceed downwards until they reach a point just 

 above the calyces, where they join several other bun- 

 dles forming a mass of tubules which empty into the 

 calyces. There are several such masses in one kidney. 

 These masses are called the medullary substance of 

 the kidney. The beginning of the medullary substance 

 is nearly like the fingers of your hand. Hold your 

 hand up before you and both extend and separate your 

 fingers. You will then have a fair example of the 

 medullary rays, medullary substance, labyrinth and 

 tube of Bellini, the fingers representing the medullary 

 rays ; the spaces between them representing the laby- 

 rinth, the palms representing the medullary substance 

 and the wrist the tube of Bellini. The tube of Bellini 

 is the excretory duct of the uriniferous tubules. 



The blood vessels enter the kidney at the hilum and 

 pass upwards and give off branches to form the glorri- 

 erulus. The glomerulus is a coil of an artery, which 

 enters the capsule of Bowman at the same point where 

 the vein leaves the capsule. In this body the urine is 

 separated, in part, from the blood. (For the theory of 

 the secretion of urine, see the text on Urine.) The uri- 

 niferous tubule is the tube which carries the urine from 

 the glomerulus to the calyces of the kidney, and it 



