The physician moved his shoulders as if to shake off an unpleasant burden. “We will put that aside for the moment, and consider the question of the murder. Everything now depends on the information I expect to find waiting for me when we get back. If my diagnosis is correct, Weathered died from a poison described in the book I have told you of, _Across Sumatra_, by Captain Armstrong. The natives have some name for it which I forget, but I have called it _Upasine_.” “Upasine!” I repeated the name in stupefaction. “Yes. You have heard, no doubt--everybody has heard--of the famous upas tree. According to the tales of the old explorers, it was a tree that exhaled a deadly vapour, so that the traveller who went to sleep beneath its shelter never woke again. The bones of animals were found scattered round the trunk, and they were supposed to have perished in the same way, by going to sleep within the deadly radius.” “But surely,” I said in astonishment, “surely no one believes that any longer? I thought it had been proved to be a fable.” The great expert shook his head. “There are not many fables that haven’t some truth in them,” he pronounced. “The legendary glories of Timbuktu were dismissed at one time as travellers’ tales, but it turned out there was a city called Timbuktu on the southern edge of the desert of Sahara; that it was the great market to which the caravans from the Mediterranean coast made their way, and even that it once possessed something like a university, when it became a refuge for the Moors who were driven out of Spain. The accounts of the upas tree and its fatal shadow were dismissed in the same shallow way without any inquiry as to how they originated. Armstrong happened to be an intelligent man, and he told me that one of the objects of his exploration of Sumatra had been to find out the truth about the upas.” My incredulity began to give way before my chief’s sober words. “He started out with the conviction that bones and corpses had been found under some trees by some explorers, who had accepted the native theory that the tree cast a deadly spell on all within its range. Other travellers had tested the theory and found that it was possible to sleep under the tree in perfect safety. And so they had treated the whole thing as a pure fancy, without inquiring further. Armstrong did inquire further, and perhaps you can guess what he found?” For some moments I was hopelessly puzzled. “The leaves are poisonous, perhaps, and the sleepers die because they have eaten them?”