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 



o. 



l ( 'it.;. -405. Arrangement of apparatus for working on the isolated 

 mammalian heart. (KNOWLTON and STABLING.) 



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 Avater manometer shows the pressure in 

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

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

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



