KIDNEYS. 



341 



one being longer .and narrower than the right. From perverted 



development, the kidney of the horse is sometimes lobulated. 

 The kidney presents two surfaces and a circumference. The 



surfaces are smooth, the superior one being flattened, and 



attached to the muscles by cellular tissue ; the inferior one is 



convex, covered by and attached to the peritoneum. The cir- 

 cumference is divided into three borders; 



anterior, posterior, and internal. The 



t wo former are convex ; to the first 



is attached the suprarenal capsule. 



The internal border is slightly concave, 



being deeply notched in the centre, 



forming the " hilus, which leads to a 



cavity called the sinus. The vessels, 



nerves, and duct of the kidney join it 



in or about the hilus. 



The kidney is made up chiefly of 



the tubes of the gland, termed the 



uriniferous tubes, with blood-vessels 



and nerves, and connective tissue ; it 



is invested by a fibrous capsule, and 



contains a <?avity known as the pelvis 

 of the kidney. The capsule invests 

 the entire organ, entering the hilus 

 and covering the sinus, vessels, and 

 duct. It consists of thin, smooth, 

 fibro-areolar tissue, intimately con- 

 nected with the surface of the gland 

 by minute fibrous processes and blood- 

 vessels. On making a horizontal 

 section of a kidney, it is found to 

 consist of an external or cortical, 



H H. Larger tubes of Bellini ; t, Smaller 

 branch of the same. 



Fig. 121. 

 Structure of the kidney. AAA, Large 

 branches of renal artery ; a a. Affer- 

 ent vessels ; B B, Malpighian bodies ; 

 . 7 77 i^ c c c, Capillary plexuses formed by effer- 



and an internal or niedudary sub- ent vessels ; d. Xwlgs from renal artery ; 



stance. The cortical layer is situated 

 beneath the capsule, sending pro- 

 longations inwards into the medullary portion. It is dark 

 reddish-brown and friable, consisting of minute blood-vessels, 

 convolutions of the uriniferous tubes, lymphatics, and nerves, 

 united by areolar tissue. On examining the section with or 

 without a lens, numerous minute red points are seen in the 

 coitical portion, the Mcdpighian bodies. Each consists of 



