1. ON THE CAUSE OF THE DIASTOLE OF THE 
VENTRICLES OF THE HEART.* 
Tue existence of an active diastolé of the ventricles of the heart fol- 
lowing each systolé has been long recognised by physiologists, and 
there have been several explanations given of the phenomenon; but 
they are all subject to grave objections, and fresh methods of research 
have overthrown them one after another. 
The object of the present article is to show that this active diastolé 
is mainly dependent on the turgescence of the walls of the heart, 
consequent on the flow of blood into the coronary arteries immediately 
after the systolé. 
The experiments of Vaust in 1821, together with the known ana- 
tomical arrangement of the commencement of the aorta, strongly 
favour the supposition that during the ventricular systolé the circula- 
tion in the walls of the heart ceases on account of the close relation 
between the segments of the aortic valve and the orifices of the coronary 
arteries. 
Immediately the aortic valve is closed the impediment to the flow 
of blood into the coronary vessels is removed, and the sudden repletion 
thus caused, directly after the closure of the valve, produces an equally 
sudden turgescence of the walls of the ventricles, the auricles from 
their thinness not being similarly affected. This turgescence of the 
tissue of the heart produces an active opening out of the cavities of the 
ventricles, and in a very short time they reach their maximum size. 
The following experiment supports this theory:—take a sheep’s 
heart which has at least two inches of the aorta left on; attach the cut 
end of the aorta to a pint syringe full of water and inject; the first 
effect of this operation is the closure of the aortie valve, immediately 
after which water enters the coronary arteries, the ventricular walls 
Page 390. 
swell, and the cavities of the ventricles open out to their full extent. Page 391. 
It will be then found that the heart is tough and not easily compres- 
sible, and if it be cut in two between the apex and base, the halves 
show the cavities fully dilated, and they remain so until the water has 
escaped from the cut orifices of the vessels. The shortness of the 
coronary arteries and the sudden way in which they break up into 
minute ramifications favours the rapid turgescence of the heart walls. 
If this theory be correct it follows that there must be an absorptive 
* “Journal of Anatomy and Physiology,” III. pp. 390-3. May, 1869. 
B2 
