THE ciftcyLATioN OF THE BLOOD 



tinuous-paper kymograph. Now open the abdominal wall by an incision 

 along the median line, expose the left kidney and carefully dissect off its cap- 

 sule, taking care not to injure its artery and vein. Enclose the kidney in 

 the renal onkometer, fill the onkometer with oil, and connect it with a record- 

 ing apparatus. Brodie's bellows recorder is probably the best recording 

 apparatus for this purpose. Adjust the recording apparatus in the vertical 

 line with the manometer and signal pens. 



Stimulation of the nerves which affect the general blood pressure through 

 the medium of the heart will be found to produce changes in the volume of 

 the kidney in the same direction as the blood-pressure change. On the 

 other hand, stimuli which give variations of the blood pressure without 

 direct change in the heart itself affect the volume of the kidney independent 

 of the blood pressure: 



1. Dissect out and stimulate the splanchnic nerves just where they pass 

 through the pillars of the diaphragm. Stimulation of these nerves will 

 cause vaso-constriction in the kidney, which takes place without sharply 

 affecting the blood pressure. 



2. Stimulate the depressor nerve or the central end of the divided vagus. 

 In this case the volume of the kidney will increase though the general blood 

 pressure decreases, showing that the fall of blood pressure is due to periph- 

 eral vascular dilatation. 



3. Stimulate the peripheral end of the divided vagus so as to slow or 

 even completely stop the heart. 'The sharp fall in blood pressure is 

 now accompanied by decrease in the volume of the kidney, showing that the 

 kidney change is merely passively following that of the blood pressure. 



