ORGANS OF THE BODY. 



515 



where the ureter leaves the gland, and its nutrient blood-vessels 

 enter. 



The substance of the kidney presents for consideration two portions, 

 namely, the cortical or external, which is of a brownish red colour, and in- 

 distinct structure to the naked eye, and an internal paler medullary portion 

 of fibrous appearance. The latter is marked by fine lines converging towards 

 the hilus, and consists in most mammals of a single conoid mass with the 

 apex towards the hilus, but in the case of the human being and pig this is 

 divided into from 10 to 15 sections, whose bases lie towards the cortical 

 part of the organ, their apices being directed towards the hilus. To these 

 the name Malpigliian or medullary pyramids has been given. Between 

 them the cortical substance is 

 prolonged inwards in the form of 

 septa, known as the columnce 

 Bertini, while both portions of 

 the organ contain interstitial 

 sustentacular connective-tissue. 



Notwithstanding their want 

 of similarity in appearance, both 

 portions of the kidney consist of 

 glandular elements resembling 

 each other in many particulars. 

 These are long branching canals 

 or tubes, known as the urinifer- 

 ous tubes of Bellini. In the 

 medullary part of the organ, 

 however, they pursue a straight 

 course diverging slightly or run- 

 ning nearly parallel, and dividing 

 at very acute angles ; while on 

 their arrival in the cortex they 

 commence to turn and twist 

 upon themselves, and intertwin- 

 ing one with another (fig. 507, 

 e), terminate eventually in a 

 blind dilatation (d) which enve- 

 lopes a peculiar congeries of 

 vessels (c*, c 1 ). 



The difference of texture ob- 

 served in both portions of the 

 organ is thus explained. 



This is all that was known 



until recently about the structure of the kidney, and much difference of 

 opinion existed, besides, as regards the relations of the blood-vessels to 

 the several elements of the organ. 



We owe much to Henle for having given a new impetus to the study 

 of the histology of this organ some years ago by his interesting dis- 

 coveries. He found, namely, that the medullary substance contains, 

 besides the well-known straight tubes, with acute-angled division, which 

 open into the pelvis of the "organ, a series of finer canals arranged in loops, 

 whose convexities are directed towards the apex of the medullary pyramids 

 and which on arrival at the limits of the latter are continued into the 

 cortex. 



Fig. 507. From the cortex of the human kidney, a, 

 arterial twig giving off branches; 6, to the con- 

 geries of vessels c*, c 1 ; c, efferent vessel of the 

 latter; d, dilatations on the ends of convoluted 

 uriniferons tubes, e. 



