1028 PHYSIOLOGY 



to a tambour D. Every time that siphonage occurs there is a change 

 of pressure within the tambour, which can be registered by the lever 

 on a blackened surface. The siphon discharges the blood into a reser- 

 voir F, which is kept immersed in a vessel of water maintained at 

 any desired temperature by some source of heat. From the spiral 



FIG. 405. Arrangement of apparatus for working on the isolated 

 mammalian heart. (KNOWLTON and STARLING.) 



below F, an india-rubber tube leads to a cannula CV, which is placed 

 in the superior vena cava, all the branches of which have been tied. 

 This cannula is provided with a thermometer to show the temperature 

 of the blood supplied to the heart. A tube placed in the inferior vena 

 cava and connected with a water manometer shows the pressure in 

 the right auricle. On the recording surface we thus have a record of 

 the arterial pressure, of the output of the whole system, as recorded 

 by the tambour, and of the pressure within the right auricle. If desired 



