ADVANCED EXPERIMENTAL PHYSIOLOGY 



167 



glass tube passes through this cork and is connected with a recording 

 tambour. The finger-stall acts as the spring. 



Connect by side tubes the mercurial manometer and the Hiirthle 

 manometer with the artery in the artificial schema. Take records 



FIG. 168. Hlirthle's differential manometer. 



with each instrument on a moderately fast drum, and compare the 

 results. Connect by side tubes one side of the Hiirthle differential 

 manometer with the chamber of the pump, and the other side with 



FIG. 169. Aortic and ventricular pressure curves taken by HUrthle manometers. (Hurthle). 



1. Beginning of systole. 2. Opening of semilunar valves. 3. End of rise of ventricular 



pressure. 4. Dicrotic notch, closure of semilunar valves. 



the artery close to the valve. Take a record, and observe how the 

 instrument records the moment when the valve opens and shuts. 

 If a time tracing be taken, the time relations of the pump (ventricular 

 contraction) can be exactly determined. The period of ventricular 



