156 



THE ABDOMEN. 



and blood-vessels. Outside the medullary substance 

 and just under the capsule is the cortex, containing 

 the Malpighian bodies, blood-vessels, and the con- 

 voluted tubules or loops of Henle. Each Malpighian 

 body contains within a capsule a plexus of capillaries, 

 the glomerulus } with an afferent arteriole and an effer- 

 ent vein. The renal artery is a branch of the aorta and 

 the nerves are from the solar plexus. 



Fie. 59. A longitudinal section of FIG. 60. A Malpighian body or 



the kidney. (Leroy.) a, Renal ar- corpuscle. (Leidy.) a, Afferent 

 tery; c, cortex; TO, medulla; u, ureter. artery; e, efferent vessel; c, capil- 

 laries; k, commencement of urinif- 

 erous tubule; h, uriniferous tubule. 



The Urine. As the blood passes through the glom- 

 eruli, the urine is filtered off as it were, probably by 

 a process of transudation rather than simple filtration. 

 The cells lining the tubules also play an important 

 part in its formation, not by secreting new substances 

 but by taking up those brought by the blood and dis- 

 charging them into the convoluted tubules, from which 

 the urine passes through the straight tubules of the 

 medulla to the pelvis, to be carried thence by the ure- 

 ter. The process of the formation of the urine, there- 



