Page 392. 
4 ON THE CAUSE OF THE DIASTOLE 
force exercised in both the ventricles immediately after the closure of 
the aortic valve, and Marey found that to be the case when he placed 
in either ventricle an ampoule registering negative pressures only. 
The relation between. the cardiograph. traces from the ventricles 
and aorta throw so much light on the point under consideration that a 
detailed description of them will not be out of place. 
The diagram is taken from Marey’s work De la Circulation du 
Sang, p. 189. : ee 
| 
w A 
S Aa 
/ 
[ ea * 
ABE | 
~J | LA 
= el 
ONT. 2 N ra 
f 
— V4 Pe ad 
aa ee eS ee 
TES 5 AR RT RA ELIE SITS IIT a a 
No. I is the trace from the left ventricle. 
No. IT is from the aorta. 
Simultaneous events are recorded in the same longitudinal line, and the traces 
by their rise and fall indicate alterations of pressure in the ventricle and aorta 
respectively. 
No more reference will be here made to the systolic than is neces- 
sary to explain the diastolic movements. 
Towards the end of the cardiac systolé, the pressure which con- 
tinues to increase in the ventricles (v) diminishes in the aorta (b), 
because then the latter receives less blood from the heart than it 
transmits to the capillaries. 
After this, it is considered by Marey that the undulation # in the 
upper trace corresponds with ¢ in the lower, and that they are both 
caused by the closure of the aortic valve; he also thinks the fall 
between « and z in the upper trace to be due to the relaxation of the 
ventricle, and, without explaining why, states that at that moment the 
pressure falls ordinarily below zero. But on carefully looking at his 
own diagram, as copied above, it is clearly seen that the undulation c 
in the aortic slightly precedes x in the ventricular trace, and this, 
together with the results obtained by Chauveau, by means of his com- 
