AXATOMY OF THE KCDXEYS. 149 



applied to the basement-membrane. They are thick, irregu- 

 larly polygonal in shape, and contain numerous albuminoid 

 granules. They present one, and occasionally, though rarely, 

 two granular nuclei with one or two nucleoli. They are very 

 liable to alteration, and are only seen in the normal condi- 

 tion in a perfectly fresh, healthy kidney. Their diameter is 

 about 15 1 00 of an inch. The calibre of the tubes is reduced 

 by the thickness of their lining epithelium to -g-J-g- or -g-J-g- of an 

 inch. 



Cortical Substance. In the cortical portion of the kid- 

 ney are found numerous tubes, differing somewhat from the 

 tubes of the pyramidal portion in size and in the character 

 of their epithelial lining, but presenting the most marked 

 difference in their direction. These tubes are somewhat 

 larger than the tubes of pyramidal substance, and are very 

 much convoluted, interlacing with each other inextricably 

 in every direction. Scattered pretty uniformly through this 

 portion of the kidney, are rounded or ovoid bodies, about 

 four times the diameter of the convoluted tubes, known as 

 the Malpighian bodies. At one time there was considera- 

 ble difference of opinion with regard to the relation of these 

 bodies to the tubes ; but the researches of Bowman, Isaacs, 

 and later anatomists, have established, without doubt, the 

 fact that they are simply flask-like terminal dilatations of 

 the tubes themselves. 



As the result of the researches of Bowman, Goodsir, and 

 Isaacs, the cortical portion of the kidney is now regarded as 

 composed of a delicate fibrous matrix, 1 which forms a sort 

 of skeleton for the support of the secreting portion with its 

 blood-vessels. The tubes of this portion are convoluted and 

 somewhat larger than the straight tubes, but are continuous 

 with them, terminating finally in the Malpighian bodies. 



1 The fibrous matrix of the kidney was first described in detail by Goodsir, 

 in 1842 (loc. cit.\ but its existence was afterward denied by such eminent anat- 

 omists as Henle, Frerichs, and others. This structure was very accurately de- 

 scribed by Isaacs (op. cit.\ and has since been admitted by most observers. 



