242 



PHYSIOLOGY OF THE HEART 



[CII. XX. 



the auricular and ventricular rises of pressure being merged into one 

 continuous rise. 



2. That the auriculo-ventricular valves are closed before any 

 great rise of intraventricular pressure above that which results from 

 the auricular systole occurs (a, fig. 250). The closure of this valve 

 does not produce any notch or wave. 



3. That the semilunar valves open at the point in the ventricular 



FIG. 250. Curve from left ventricle obtained by Rolleston's apparatus ; the abscissa shows 

 atmospheric pressure. 



systole, situated (at c) about or a little above the junction of the 

 middle and upper third of the ascending line (A B), and the closure 

 about the shoulder (D). 



4. That the minimum pressure in the ventricle may fall below 

 that of the atmosphere, but that the amount varies considerably. 



Another method of overcoming the imperfections of Marey's tam- 

 bour is by the use of Hiirthle's manometer (fig. 244). In this the tam- 

 bour is very small, the membrane is made of thick rubber, and the 



FIG. 251. Hiirthle's Manometer. 



whole, including the tube that connects it to the heart, is filled with 

 a strong saline solution (saturated solution of sodium sulphate). 



The tracing obtained by this instrument, when connected with 

 the interior of the ventricle, is represented in the next figure. 



The auricular systole causes a small rise of pressure A B ; it lasts 

 about "05 second. It is immediately followed by the ventricular con- 

 traction, which lasts from B to D. From B to c the ventricle is 

 getting up pressure, so that at c it equals the aortic pressure. This 

 takes '02 to "04 second. Just beyond c the aortic valves open, and 

 blood is driven into the aorta; the outflow lasts from c to D ('2 



