STRUCTUEE OF THE KIDNEY. 



545 



of an inch thick. These cells have also clear, non-granular con- 

 tents; while those of the tubuli contort! contain, besides the usual 



Fig 376. 



Section of the cortical substance of the human kidney. A, A. Tubuli uriniferi divided trans- 

 versely, showing the subconoidal epithelium in their interior. B. Malpighian capsule ; a, its affer- 

 ent branch of the renal artery ; b, its tuft of capillaries ; c, c, secreting plexus (of vessels) formed by 

 its efferent vessels ; d, d, fibrous stroma. 



round nuclei, a finely granular albuminous (Kolliker) substance in 

 the fluid contents, and generally some dark oil-drops, and more 

 rarely, granules of yellow pigment. (Fig. 132, A & B.) The last 

 cells alone probably secrete the urine. (Toddand Bowman!) 



2. The vascular (cortical) portion of each lobule consists of the 

 tubuli contorti, just described, the Malpighian bodies, the vessels 

 carrying blood to and from the latter, and the stroma of embryonic 

 areolar tissue connecting all these elements together. The Malpi- 

 ghian bodies extend to within 6 ^ of an inch of the surface of the 

 kidney on the one hand, and in the columns of Bertini even to the 

 hilus of the kidney on the other. Each of these is a rounded mass 

 (glomerulus), consisting of a close convolution or tuft of capillaries 

 soW to rsVo of an inch in diameter; inclosed in a capsule and sup- 

 plied by an artery (vas afferens\ TsW to ei^ f an ^ ncn i n diameter. 

 This convolution of vessels is received into the dilated extremity 

 of a tubulus contortus ; and its capsule is apparently the continuous 

 basement-membrane of the tubulus, somewhat thickened. Thus 

 the Malpighian body is virtually inclosed in the extremity of the 

 tubulus; and it amounts to the same thing, practically, if it be said 

 that the tubulus ends like the larger closed extremity of a retort, 

 after having first inclosed the Malpighian body. (Figs. 377, and 131.) 

 A vessel also emerges from the tuft within, through the capsule (the 

 vas efferens) not a vein, however, as might be expected ; the pre- 

 35 



