644 



PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



The principal constituent of the urine which is removed by a process 

 of filtration is, of course, water. Therefore, in the quantity of urine, 



FIG. 268. BLOOD-VESSELS AND URINIFEROUS TUBULES OF THE KIDNEY 



(SEMI-DIAGRAMMATIC). (LandOtS.) 



A, capillaries of the cortex ; B, of the medulla ; a, interlobular artery ; 1, vas afferens ; 2, vas 

 efferens ; r e, vasa recta ; c, venae rectae ; v v, interlobular vein ; S, origin of a vena stellata ; i i, Bow- 

 man's capsule and glomerulus; X X, convoluted tubules; 1 1, Henle's loop; n n, junctional piece; o o, 

 collecting tubes ; O, excretory tube. 



which, of course, means quantity of water, the variations in the activity 

 of the process of filtration may be mainly made out. Wherever the 



