2OO 



EXCRETION BY THE KIDNEYS AND SKIN 



quality of the urine ; secretion of the upper dorsal cord tem- 

 porarily arrests the secretion; mental emotions, such as 

 fright, anxiety, etc., also modify the flow. All these circum- 

 stances, and many others, indicate some control over the ac- 



\ 

 FIG. 59. Blood-vessels of the kidney. 



A, capillaries of cortex; B, of medulla; a, interlobular artery; i. vas afferens; 

 2, vas efferens; i, e, vasa recta; VV , interlobular vein; S, origin of a stellate 

 vein; i, i, Bowman's capsule and glomerules; P, apex of papilla; C, capsule of 

 kidney; e, vasa recta from lowest vas efferens. (Stirling.) 



