250 CIRCULATION. 



25 Effect of extract of Suprarenal Capsule on the flow 

 through the blood vessels. 



Required : Glass aortic canula for the frog, connected by a rubber 

 tube 15 cm long to a glass funnel; a 50 cc measure with a funnel and a 

 retort stand. 



Pith the frog and plug the opening. 



After exposing the heart through a window in the sternum, 

 introduce the canula into the left aorta and tie it in. Ligature 



o 



the right hand one. 



Incise the sinus so that the fluid may pass freely from 

 the veins. 



The frog is to be suspended by its head with threads attached 

 to the ring of a retort stand, and with its legs hanging into the 

 funnel in the mouth of the glass measure. 



The funnel, with rubber tube attached and closed with a clip, 

 is supported on another ring of the retort stand on a level 

 with the frog's head. Fill it and the canula with normal saline 

 arid connect them, being careful to exclude air bubbles. 



The saline solution is next caused to flow through the vascular 

 , system of the frog, and the quantity which passes collects in 

 the measure. 



The height of the fluid is read off at short intervals (1 to 3 

 minutes), and is recorded in a tabular form in your note-book. 



After a constant rate of flow is established, in from 5 to 10 

 minutes, substitute suprarenal extract for the saline. 



Detach the rubber tube from the canula, empty, and fill the 

 funnel and tube with the extract; connect again to the canula 

 and continue the observation. 



A decrease will indicate obstruction to the flow due (Oliver 

 and Schafer) to contraction of the small arteries. 



