HYPEILEMIA OF THE KIDNEY. 3 



skin in the cold stage of intermittent fever. In the second stage of 

 Bright's disease, compression of the vessels of the cortical substance, 

 by the distended urinary tubules, also gives rise to collateral fluxion in 

 the medullary substance of the kidney ( Virchow). 



4. Dilatation of the afferent vessels, from palsy of their muscular 

 elements, seems to be the principal cause of that arterial hyperaemia 

 of the kidney, the existence of which is revealed by the discharge of 

 a large quantity of limpid urine in certain spasmodic diseases (urina 

 spastica). 



. ' ^5. Fluxionary hyperaemia is found in the vicinity of inflamed regions 

 and deposits of morbid product. This form of hyperaemia we have 

 already endeavored to account for, in treating of an analogous condi- 

 tion in other organs, ascribing it to a loss of tone in the tissues, and 

 to a dilatation of their capillaries, whose walls are ill supported by the 

 surrounding relaxed parts. 



6. Renal hyperaemia complicates inflammatory disease of the urinary 

 passages, especially 'disease of the pelvis of the kidney. 



7. The renal hyperaemia which sometimes attends the use of can- 

 tharides, balsam of copaiba, and similar drugs, as well as that which 

 accompanies certain infectious diseases, especially scarlatina, measles, 

 typhus, and cholera, seems to be of similar origin. However, the affec- 

 tions of the kidney which arise from the diseases above named cannot 

 all be attributed to hyperaemia. Many of them belong to the class of 

 maladies which we shall describe as parenchymatous degeneration of 

 the kidney, in Chapter VII., and which, undoubtedly, are capable of de- 

 veloping without the occurrence of hyperaemia. This io equally true 

 of the renal affections which so often accompany pregnancy. 



Obstructive engorgement of the kidney arises from causes similar 

 to those which induce engorgement of the liver (see Volume I.), so 

 that the two diseases often accompany one another ; but it will readily 

 be understood, from what has already been said as to the peculiar 

 character of the hepatic circulation, that engorgement of the liver 

 usually is of earlier occurrence and greater intensity than engorgement 

 in the kidneys. Engorgement of the kidney arises: 1. In uncompen- 

 sated valvular disease of the heart; 2. In structural disease of the 

 heart, which depresses the functional energy of the organ ; 3. When 

 the vigor of the heart is impaired by a condition of marasmus; 4. In 

 disease of the lungs, which causes compression or wasting of the pul" 

 mohary capillaries; 5. In conditions in which the aspiration of the 

 blood to the thorax is arrested ; 6. In rare instances, contraction and 

 closure of the vena cava or emulgent veins, by compression or throm- 

 bosis, give rise to engorgement of the kidney, but the hyperaemia 

 arising in such cases is of very great intensity. 



