CHAPTER XIV. 



THE KIDNEY. 



Br ABRAHAM MAYER, M.D., 



Curator of the Manhattan Eye and Ear Hospital, New York City. 



General plan of structure. The glandular substance of the 

 kidney is divided into two parts, an external or convex por- 

 tion, called the cortical substance, or cortex, and an internal 

 or concave portion, the medullary substance, or medulla. 

 This division can be readily seen by cutting a kidney into two 

 equal parts in the line of its long diameter. An intermediate 

 zone, which separates the cortical from the medullary sub- 

 stance, is called the boundary layer of the kidney. The whole 

 organ is enveloped in a fibrous membrane, the capsule. 



The medullary substance contains the pyramids of the kid- 

 ney, and is therefore also called the pyramidal portion. The 

 apex of each pyramid, the papilla, projects into a special arm 

 of the renal pelvis, viz., a calyx; the base or expanded por- 

 tion is directed toward the cortical substance, and sends pro- 

 longations into the latter. 



An examination of the cortical substance shows it to be 

 composed of two distinct varieties of tissue, running parallel 

 to one another toward the free surface. One has a fibrous ap- 

 pearance, and is composed of cylindrical cords. It is a con- 

 tinuation of the pyramids. These pyramidal prolongations ' 

 (Henle) are also called medullary rays (Fig. 89). The other 

 portion, situated between the prolongations, is a granular-look- 

 ing material, called the cortical substance proper, or labyrinth 

 of Ludwig.* The latter contains numerous small bodies, 

 which are of a distinctly red color when there is a large 



1 Ludwig und Zawarykin : Zeitschrft f iir rat. Med,, 1863. They are also called 

 the prolongations of Ferrein. 



2 Ludwig : Strieker's Manual, p. 461. 



