172 PKACTICAL PHYSIOLOGY 



is opened and the greater splanchnic nerve exposed by blunt dissec- 

 tion where it lies just outside the supra-renal capsule. A ligature 

 is tied round the nerve and the peripheral end stimulated. 



Note that blood pressure rises. A cannula bent at right angles 

 is placed in the bladder, and the left kidney in the oncometer. 

 The kidney is laid on one of the pieces of the oncometer, its 

 vessels being placed in the groove. The india-rubber bag filled with 

 water at 38 C. is placed round it, and the other half of the 

 oncometer put in position and the rubber bands applied. The tube 

 of the rubber bag is connected with a water manometer, the water 



FIG. 174. Arterial pressure (I) and oncometer tracing (2) of kidney volume. Be- 

 tween the points starred the 10th dorsal root was excited. The time is marked in 

 seconds. (Bradford.) 



being coloured with methylene blue. The manometer should show 

 pulsations. Cover the abdomen with warm compresses of wool 

 wrung out from hot 0*75 per cent, saline solution. Measure the 

 outflow of urine for five minutes, and note the effect of stimulating 

 the splanchnic nerve. 



Note the effect of injecting 30 c.c. physiological salt solution into 

 the jugular vein. 



So long as the venous pressure is constant any increase in renal 

 volume will denote increased blood-pressure in and increased Wood-flow 

 through the kidney. The secretion of urine varies as the volume of 

 blood passing through the kidney per minute. (By dividing the renal 

 nerves and exciting the spinal cord or vaso-motor centre the greatest 

 rate of blood-flow through the kidney can be produced.) Ligature of the 



