OF THE URINE. 299 



492. A kidney, if divided horizontally, presents two 

 substances; the exterior, called cortex; the interior, 

 medulla. 



Each abounds in blood vessels, but the cortical por- 

 tion has likewise very minute colourless vessels which 

 secrete the urine ; * the medullary part contains those 

 which carry it off. 



These secreting ducts, arising from the arteries in the 

 manner formerly described, (471) are united with glome- 

 rules which adhere to the cortical part and constitute 

 the greatest portion of it. They may be readily dis- 

 tinguished by their angular course from the excreting 

 or Bellinian tubes, in which they terminate. These, 

 pursuing a straight course, run from the cortical to the 

 medullary substance, which principally consists of 

 them, and, after they have coalesced into fewer trunks, 

 their mouths perforate, like a sieve, the papilla of the 

 pelvis of the organ.f 



493. These papillae usually correspond in number 

 with the lobes which form the kidneys, and they convey 

 the urine, secreted in the colourless vessels of the cortex 

 and carried through the Bellinian tubes of the medulla, 

 into the infundibula, which finally unite into a com- 

 mon pelvis. 



494. The pelvis is continued into the ureters, which 

 are membranous canals, very sensible, lined with mucus, 

 extremely dilatable, generally of unequal size in the 



* These secreting ducts appear to have imposed upon Ferrein as a new 

 description of vessels, which he called neuro-lymphatics or white tubes, and of 

 which he imagined the whole parenchyma of the viscera to be composed. He 

 affirmed that they were of such tenuity, that their length in each kidney of an 

 adult man was equal to 1000 orgyiae (60,000 feet) or 5 leagues. 



t Enstachius, tab. xi. fig. 10. 



