CIRCULATION OF THE BLOOD. 



Bleed again, if necessary, until the blood pressure ceases to re- 

 cover. Now introduce into the jugular vein, slowly, o.8-per-cent 

 NaCl solution, until 50 or 100 c.c. have been transfused. Does the 

 pressure again rise ? If not, continue the perfusion. 



Perfuse four or five times as much of the salt solution as there 

 was blood lost. Is there any noticeable rise of pressure above the 

 normal ? If not, explain 



7. Shock and Blood Pressure. Prepare another rabbit for 

 blood-pressure recording, isolating the vagus and depressor nerves 

 at the same time. Take a normal blood-pressure tracing. While 

 this is being done, stimulate the peripheral end of the vagus. 

 Take another tracing, stimulating the depressor nerve. These 

 tracings will serve as checks to the results obtained later. 



While the pressure tracing is being taken, open the abdomen by 

 a long median incision. Expose and handle the abdominal viscera. 

 What is the effect on the blood pressure ? 



If the pressure has fallen, stimulate the depressor nerve. Does 

 the pressure fall still more ? 



While the pressure is low, inject into the jugular vein 2 c.c. of a 

 i to 10,000 solution of adrenalin chlorid. What is the effect on 

 blood pressure and rate of the heart-beat ? 



The adrenalin effect will disappear after a short time. Cut both 

 vagus nerves and repeat the adrenalin injection. Is there any dif- 

 ference in effect on the rate of the heart-beat as compared with the 

 first result obtained ? 



XXV. PERFUSION OF THE RABBIT'S HEART. 



Bleed the rabbit of experiment 7 from both carotids, and defi- 

 brinate the blood as shed. Mix this with equal parts of o.8-per- 

 cent NaCl solution which has been warmed to 37 C. 



Open the thorax. Excise the heart which will probably con- 

 tinue to beat. Introduce and tie a small cannula into the opening of 

 one coronary artery where it leaves the aorta. Free the cannula of 

 air by filling it with physiological saline. Place the defibrinated 

 blood mixture in a bottle with a side piece and resting in a water- 



