BLOOD PRESSURE 77 



whose brain has been destroyed, tie off one aorta and fasten 

 a cannula into the other so that it will lead away from the heart. 

 Air must not be allowed to enter the system on any account. 

 Hang the frog toes down and allow the fluid to escape from 

 an incision in the sinus venosus. Determine the rate of flow 

 in cc. per minute for Ringer's solution. This can be done either 

 by measuring the inflow from a burette or by collecting the out- 

 flow in a graduated cylinder. Next perfuse with Ringer's 

 solution containing 0.1% NaNO 2 . What is the rate now? 

 Wash out the latter fluid with Ringer's solution, then perfuse 

 with Ringer's solution containing adrenalin. 



Although adrenalin causes constriction of the blood vessels 

 in the frog and under certain conditions in mammals, small 

 quantities of adrenalin cause dilatation of the vessels supplying 

 skeletal muscle in most mammals, when injected into the general 

 circulation. 



