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 even to the stimulus of galvanism. The diluted acid has not always this effect. In the experiments of Coullon the heart and intestines contracted, and the voluntary muscles continued contractile, after death as usual. So too Mr. Blake remarked both by inspection of the body after death, and by means of the hæmadynamometer during life, that, when the poison is introduced directly into a vein, so as to prove fatal in forty-five seconds, the contractions of the heart, though irregular, are not materially impaired in energy. On the other hand Schubarth states that the heart is never contractile, although the intestines and voluntary muscles retain their contractility. The reason of these discrepant statements is that, as I have had occasion to observe, a considerable difference really prevails in experiments conducted under circumstances apparently the same. In eight experiments on cats and rabbits with the pure acid the heart contracted spontaneously, as well as under stimuli, for some time after death, except in the instance of the rabbit killed with twenty-five grains, and one of the cats killed by three drops applied to the tongue. In the last two the pulsations of the heart ceased with the short fit of tetanus which preceded death; and in the rabbit, whose chest was laid open instantly after death, the heart was gorged and its irritability utterly extinct. The later researches of Dr. Lonsdale likewise show great varieties in the condition of the heart; and he has been led to conclude that the diluted acid does not perceptibly influence the heart, while the pure acid enfeebles it, if introduced into the stomach, but arrests it, if injected into the wind-pipe.

The experiments of Emmert, Coullon, and Krimer show that the diluted acid acts most energetically through the serous membranes, and next upon the stomach; that it also acts with energy on the cellular tissue; that it has no effect when applied to the trunks or cut extremities of nerves, or to a fissure made in the brain or spinal marrow; that its action is prevented when the vessels of any part are tied before the part is touched with the poison; that its action is not prevented by previously dividing the nerves; and that it may sometimes be discovered in the blood after death by chemical analysis, and frequently by the smell when analysis cannot succeed in separating it. These results favour the supposition that hydrocyanic acid acts through the medium of the blood-vessels. But the extreme rapidity of its operation in large doses is usually considered incompatible with an action through the blood, or any other channel except direct conveyance along the nerves. The tremendous rapidity of action indicated by the experiments of Magendie, or of Mr. Macaulay (p. 543), of M. Robert, as well as in some of those performed by myself,—certainly appears rather inconsistent with the notion, that the acid must enter the blood-vessels before producing its effects.

This acid acts on the brain and also on the spine independently