THE CIRCULATION 123 



brought about by the fact that the abdominal blood-vessels innervated 

 by this nerve, lose their tonus and relax. Consequently, a certain 

 quantity of blood will now find its way from the general circulation 

 into the relaxed blood-vessels of the splanchnic organs. 



Apply the shielded electrodes to the distal (abdominal) end of the 

 divided nerve. Replace the abdominal organs and cover the abdomen 

 with a warm, moist cloth. Record the blood-pressure and stimulate 

 the splanchnic nerve as described above. Owing to the lower general 

 pressure, the rise will now be more pronounced. Disconnect the man- 

 ometer and ligate the carotid artery. 



2. The Vasomotor Supply of the Kidney. Procure an oncometer 

 large enough to contain the kidney of this animal. Fill the outer com- 

 partments of this instrument with warm water until their membranous 

 inner walls have become moderately distended. Separate the left 

 kidney from the fatty tissue surrounding it, but do not injure its cap- 

 sule. Place the lower hemispheric part of the oncometer underneath 

 this organ. Adjust its cover so that the , kidney assumes a central 

 position between- the rubber membranes, taking special care that its 

 blood-vessels as well as the ureter pursue a perfectly normal course 

 through the slit-like lateral orifice of the oncometer. Connect the 

 compartment in the cover of this instrument by means of a piece of 

 rubber tubing with a membrane tambour or piston recorder. It is not 

 essential that this connecting tube be filled with water. Cover the 

 abdomen with a warm, moist cloth. 



Register the excursions of the recording lever upon the smoked 

 paper of a slowly revolving kymograph. Observe that the volume of 

 the kidney undergoes cardiac and respiratoiy variations, i. e., it is 

 increased during each systolic phase of the heart and suffers a more 

 general increase during the entire inspiratory period. 



Temporarily obstruct both femoral arteries. Note the effect upon 

 the volume of the kidney. Explain. Temporarily occlude the carotid 

 arteries. Observe the change in the volume of the kidney. Explain. 



Adjust the shielded electrodes to the distal end of the divided left 

 greater splanchnic nerve. While registering the volume curve of the 

 corresponding kidney stimulate this nerve with a quickly interrupted 

 current of moderate strength. Account for the decided reduction in 

 its volume. Kill the animal by an excessive amount of ether. 



Dissect the region of the left kidney and adrenal body. Identify 

 the organs on the opposite side, and also the suprarenal, mesenteric, and 

 celiac ganglia and plexuses of the solar sympathetic system. Trace 

 the greater splanchnic nerve into the thorax, identifying the thoracic 

 sympathetic nerve and stellate ganglion. Enucleate the adrenal bodies. 

 Bisect them and identify their cortical and medullary portions. 



3. Vasomotor Phenomena in Man. Fill a large beaker with ice- 

 water and another with water heated to 40 C. Introduce your hands 

 for a short time. Withdraw, and note the effect upon the color and 

 condition of the skin. Explain. 



