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EXCRETION 



Renal Nerves. Vaso-constrictor and vaso-dilator nerves are sup- 

 plied to the blood-vessels of the kidney, but no clearly denned secretory 

 nerves have yet been demonstrated for the organ. The vascular nerves 

 arise out of the anterior spinal roots (Bradford), chiefly the eleventh to the 



FIG. 290. Malpighian Capsule and Tuft of Capillaries, Injected through the Renal Artery 

 with Colored Gelatin, a, Glomerular vessels; b, capsule; c, anterior capsule; d, glomerular artery; 

 e, efferent veins; /, epithelium of tubes. (Cadiat.) 



FIG. 291. Diagrams Illustrating Stages in the Development of the Malpighian Capsule. In i 

 and 2 the developing blood-vessel is approaching the blind end of the capsule. In 3 the tubule is 

 beginning to invaginate and enclose the capillary. In 4 and 5 later stages are shown. The cells 

 forming the two layers of the capsule grow very thin. (Bailey.) 



thirteenth dorsal nerves. They reach the kidney by way of the splanchnic 

 nerves and the renal plexus to the renal artery along which they run into 

 the substance of the kidney. Berkeley has demonstrated nerve plexuses 

 about the arterioles and around Bowman's capsule. Terminal knob-like 



