440 



Fig. 120.* 



CHAPTER XV. 



THE KIDNEYS AND THEIR SECRETION. 



Structure of the Kidneys. 



THE kidney is covered on the outside by a rather tough 

 fibrous capsule, which is slightly attached by its inner sur- 

 face to the proper substance of the organ by means of very 

 fine fibres of areolar tissue and minute blood-vessels. 

 From the healthy kidney, therefore, it may be easily torn 

 off without injury to the subjacent cortical portion of the 



organ. At the hilus or 

 notch of the kidney, it 

 becomes continuous with 

 the external coat of the 

 upper and dilated part of 

 the ureter. 



On making a section 

 length-wise through the 

 kidney (fig. 120) the main, 

 part of its substance is 

 seen to be composed of 

 two chief portions, called 

 respectively the cortical 

 and the medullary portion, 

 the latter being also some- 

 times called the pyramidal 

 portion, from the fact of its being composed of about a 



* Fig. 120. Plan of a longitudinal section through the pelvis and 

 substance of the right kidney, ; a, the cortical substance ; b, b, broad 

 part of the pyramids of Malpighi ; c, c, the divisions of the pelvis 

 named calyces, laid open ; c?, one of these unopened ; d, summit of the 

 pyramids or papillae projecting into calyces ; e, e, section of the narrow 

 part of two pyramids near the calyces ; p, pelvis or enlarged divisions of 

 the ureter within the kidney ; u, the ureter ; s, the sinus ; h, the hilus. 



