184 Active Power of Dilatation of the Heart. [March, 



the action of the elastic property of the auricles and ventricles, 

 to be either ideal, or to be so extremely feeble, as to be capable 

 of evading our senses under the most favourable situation in 

 which we can place the organs for inspection. For I can 

 scarcely conceive it possible to devise more decisive modes of 

 ascertaining the existence of such a power, though ever so 

 trifling, than those had recourse to. 



Further, as the action of an elastic substance is as perfect 

 after the extinction of life, until the process of putrefaction 

 destroys its texture, as during the existence of the animal ; by 

 examining a heart detached, after its absolute death, or after 

 its utmost contraction by the vis mortua, we can readily 

 satisfy ourselves, whether the walls of the ventricles have 

 any elastic property that can be appreciated. If we find a heart 

 contracted, and on pressing its body so as to flatten it, that it 

 does not present to our senses a disposition to recover its natural 

 shape similar to what we witness in the truly elastic arteries 

 whose roots are attached to its base, what inference are we to 

 draw? Why certainly we must need infer that it possesses no 

 greater elastic property than muscles in common. The condition 

 of the heart greatly depends on the state of the animal when 

 killed. Fat beasts (more particularly sheep), from their un- 

 wieldiness, and from the action of their diaphragms being 

 restrained by their obesity, are easily overdriven, and sometimes 

 on their way to the slaughter-house, to prevent their suffocating, 

 they are obliged to be " stuck; " or from urgency, they are killed 

 while yet breathless and ready to faint. The right ventricle of 

 the heart of an animal killed in such a plight is found to be 

 gorged, and the reason appears to me to be obvious. As the 

 blood is more or less obstructed in its passage through the 

 lungs, previous to the sticking of the animal, the pulmonary 

 artery and the cavities of the right side of the heart are necessa- 

 rily more or less gorged, and the ventricle and pulmonary artery 

 must remain so ; for during the time the animal is bleeding to 

 death, a small portion only of the blood which they contain at 

 the time the animal is stabbed, can pass into the system of the 

 pulmonary veins, for want of pure air in the air cells of the lungs 

 to enable it to undergo the mysterious change in the rete Mal- 

 pighii. Thus the right ventricle will be large and flabby, or 

 with its muscular fibres relaxed after the pluck is extracted ; for 

 in consequence of its being retained in a state of extension, the 

 action of the vis mortua is prevented from affecting its muscular 

 fibres. When an animal is killed by dividing the blood-vessels 

 of the neck without any previous obstruction in the lungs, then 

 no engorgement can take place in the right ventricle, for the 

 blood rushes with unusual impetuosity towards the point where 

 there is the least resistance, and in a few minutes nearly the 

 whole of the blood in the body escapes through the artificial out- 



