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?”
“Not a bad guess. No; Armstrong discovered a minute fungus that grows in the soil round the root of the upas tree, and apparently nowhere else. The animals that browse on this fungus are overcome by sleep, and die without waking. It contains a soporific poison which acts rather like opium at first, but has a peculiar effect on the skin, which it dries up like parchment. You were the first to draw my attention to the parchment-like appearance of Weathered’s face, you may remember.”
I did remember. A burden was lifted from my heart by the recollection. Whatever peril I might stand in from the law, I could assure myself at last that I was not a murderer. The drug I had administered to Violet’s persecutor had contained no grain of any other poison than opium. And now I need not fear that I had given him an overdose of that. He had died, he must have died, from the poison discovered by the explorer of Sumatra. And that meant that he had died by some other hand than mine.
The specialist continued his explanation.
“You see now why I asked you to make no more remarks on what you saw. Whoever used this poison probably believes that he is the only person who possesses any, or even knows of its existence. Armstrong’s book attracted very little notice. It was badly written, for one thing, and there were no illustrations, a fatal omission in a book of travels nowadays. I don’t think there was a word about this discovery in any of the reviews. Naturally the murderer thinks that he is safe from detection.”
“How did you come to hear of the poison?” I ventured to ask.
“In the simplest way. Captain Armstrong himself brought me a sample to analyse.”
Of course! I could have kicked myself. Tarleton was the one man to whom any such discoverer would be certain to come for an opinion.