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HANDBOOK OF PHYSIOLOGY. 



by varying the distance between the holders (G.G.) and the central part 

 of the steel ribbon to which the lever is attached. 



Rolleston's conclusions are as follows : 



1. That there is no distinct and separate auricular contraction 



Fig. 171 . Endocardia! pressure-curve from the left ventricle. The thorax was opened and a 

 canula introduced through the apex of the ventricle: abscissa is line of atmospheric pressure. G 

 to D represents ventricular contraction; from D to the next rise at G represents the ventricular 

 diastole. The notch at the top of which is p is a post- ventricular rise in pressure from below that 

 of the atmosphere and not a pre-systolic or auricular rise in pressure. 



marked in the curves obtained from either right or left ventricles, the 

 auricular and ventricular rises of pressure being merged into one con- 

 tinuous rise. 



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

 rise of pressure within the ventricle above that which results from the 

 auricular systole (, fig. 172). The closure of the valve occurs probably 



Fig. 172. Curve with dicrotic summit from left ventricle abscissa shows atmospheric pressure. 



in the lower third of the rise A B (fig. 172), and does not produce any 

 notch or wave. 



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

 systole, situated (at G) about or a little above the junction of the mid- 

 dle or upper third of the ascending line (A B), and the closure about or 

 a little before the shoulder (D). 



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

 of the atmosphere, but that the amount varies considerably. 



