"The heart of the eel and of some fishes, and of animals even, when taken out, pulsates without auricles; indeed, if you cut it in pieces you shall see its divided parts contracting and relaxing separately; so that in these creatures the body of the heart pulsates and palpitates after the auricles have ceased to move. Is this, however, peculiar to the animals which are more tenacious of life, whose radical moisture is more glutinous, or rich, and sticky,[243] and not so readily dissolved? For in eels the thing is apparent even in their flesh, which retains the power of motion after they have been skinned, drawn, and cut in pieces."[244] At this point we may recall the following words of our author:-- "I affirm also that in this way the native heat or innate warmth, being the common instrument of all the functions, is likewise the prime efficient cause of the pulse."[245] Should we hazard the improbable guess that Harvey meant his cause of the heart-beat to be effective only in warm-blooded animals, we must remind ourselves that it certainly was well known to him as to all the other physicians of his day that the heart of the mammal beats after excision. If few had made experiments, all had studied Galen; and Galen cites the beating of the heart after excision as evidence that its beat does not depend upon the nervous system, the context making it obvious that he refers to the heart-beat of the mammal. Moreover, he makes it evident that the striking phenomenon in question must have been seen by the ancients at the altar, as an incident of sacrificial rites.[246] This fact makes it easy to understand how it happened that earlier still, at least two centuries before Galen's time, the layman Cicero, one of Harvey's favorite authors, should have made a stoic say:-- "It has often been observed that, when the heart of some animal has been torn out, it palpitates with a mobility which imitates the swiftness of fire."[247] Moreover, thirty-five years before Harvey was born, even the beating of the excised human heart had been seen by Vesalius, and referred to in his celebrated treatise on anatomy, as an incident of one of the barbarous executions of the sixteenth century.[248]