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These cardiac centres are in a more or less continuous state of so-called automatic activity, which is capable of being exalted, depressed, or otherwise modified by impulses proceeding from the heart itself and blood-vessels, from the somatic and splanchnic periphery as well as from the higher regions of thought and feeling.
We have, as a rule, no direct voluntary control over the heart's action—perhaps a wise provision of Nature against the temptation to try foolish and dangerous experiments. Cases, however, are on record in which, apparently hy voluntary effort, the action of the heart has been inhibited or rendered almost imperceptible. The best authenticated instance of this kind is that of Colonel Townsend (related by Cheyne in his "English Malady," 1733), who was able at will to throw himself into such a state of suspended animation that his heart and breathing ceased to be appreciable by ordinary tests. More wonderful things have been related of the Indian fakirs. We do not as yet know the real mechanism of this voluntary hybernation, but Ed. Weber proved on himself that the action of the heart can be reduced ad
