28 THE METHOD OF MAKING POST-MORTEM EXAMINATIONS. 



and finally terminate in the glomeruli or Malpighian bodies. In this 

 way the cortex of the kidney, as seen in section, is divided into alternate 

 bands of straight tubes, and convoluted tubes, with glomeruli ; both sets 

 of bauds being perpendicular to the surface of the kidney, and called re- 

 spectively medullary rays and labyrinths. About the convoluted tubules 

 and glomeruli is a rich venous plexus ; and since after death the blood 

 usually remains in this plexus and in the glomeruli, the bands containing 

 the convoluted tubules, i.e., the labyrinths, usually appear red, while the 

 medullary rays are grayish -white. In a normal kidney, therefore, the 

 cortex should be regularly striped in narrow alternating red and whitish 

 bauds, 



The average thickness of the cortex of the kidney is from 4 to 6 mm. 



If there be extensive congestion, the entire cortex is red. If the epi- 

 thelium of the tubules degenerates and fills them up, or if there are con- 

 siderable changes in the interstitial tissue, the regular bauds are lost and 

 the cortex is irregularly mottled. If the tubular epithelium becomes 

 filled with fat globules, this is indicated by an opaque yellow color of the 

 affected parts ; iu many cases, therefore, the existence of kidney lesion 

 can be recognized with the naked eye. 



If waxy degeneration be present to a marked extent, it may be mani- 

 fest by a peculiar translucent appearance of the affected parts, but in 

 most cases it is necessary to apply reagents to demonstrate it satisfac- 

 torily. The cut surface of the kidney is washed with water, to free it 

 from blood, and repeatedly brushed with an aqueous solution of iodine 

 (iodine 1 part, potassium iodide 3 parts, water 100 parts). The glo- 

 meruli and the blood-vessels are most frequently affected, and, if so, they 

 may appear as mahogany -colored dots and lines on a yellow ground. 



But this reaction is not constant, and for accurate detection of amyl- 

 oid substance, recourse should be had to other reagents applied to sec- 

 tions of the hardened tissues (see page 83). 



The pelvis of the kidney should be examined for inflammatory lesions 

 and calculi. Sometimes a whitish fluid is seen in the pelvis and can be 

 squeezed from the papillae ; this is produced by a post-mortem desqua- 

 matiou of the epithelium, but is likely to be mistaken for pus. 



PRESERVATION OP THE KIDNEY. If the kidney be not opened, the blood-vessels 

 may be injected through the renal artery, slowly and under a low pressure, with Orth's 

 fluid or Flemming's osmic-acid mixture. After the vessels are filled with either of the 

 above fluids the former are tied, and the entire organ is placed in a large quantity of the 

 injecting fluid for twenty-four hours. The kidney is then cut into small pieces, and 

 the hardening is completed in the usual way. 



In most cases, however, the kidneys will have been opened for inspection at the 

 autopsy. Then small pieces are removed from the various regions and hardened in the 

 above fluids. 



Kidneys which are to be examined for the presence of bacteria should be cut into 

 small pieces and placed at once in strong alcohol, which should be changed once or 

 twice, and in which they are permanently preserved. 



The Adrenals Suprarenal Capsules. These are, in the foetus, of an 

 ovoidal ; in the adult, of a triangular shape. They are situated at the 



