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so obvious, that, on impartial reflection from this standpoint, it seems almost absurd to persist in making the body serve two masters by deriving its actions from two radically different origins and then ascribing on the one hand the movements of our arms and legs, of our eyes, lips, throat, tongue and lungs, of the facial and abdominal muscles, to the will; while on the other hand the action of the heart, the movements of the veins, the peristaltic movements of the intestines, the absorption by the intestinal villi and glands and all those movements which accompany secretion, are supposed to proceed from a totally different, ever mysterious principle of which we have no knowledge, and which is designated by names such as vitality, archeus, spiritus animales, vital energy, instinct, all of which mean no more than x. 1
It is curious and instructive to see the trouble that excellent writer, Treviranus 3 takes, to find out in the lower animals, such as infusoria and zoophyta, which movements are voluntary, and which are what he calls automatic or physical, i.e. merely vital. He founds his inquiry upon the assumption that he has to do with two primarily different sources of movement; whereas in truth they all proceed from the will, and the whole difference consists in
1 It is especially in secretive processes that we cannot avoid recognising a certain selection of the materials fitted for each purpose, consequently a free will in the secretive organs, which must even be assisted by a certain dull sensation, and in virtue of which each secreting organ only extracts from the same blood that particular secretion which suits it and no others: for instance, the liver only absorbs bile from the blood flowing through it, sending the rest of the blood on, and likewise the salivary glands and the pancreas only secrete saliva, the kidneys only urine, &c. &c. We may therefore compare the organs of secretion to different kinds of cattle grazing on one and the same pasture-land, each of which only browses upon the one sort of herb which suits its own particular appetite. [Add. to 3rd ed.]
2 Treviranus, Die Erscheinungen und Gesetze des Organischen Lebens [The appearances and laws of organic life], vol. I pp. 178-185.
