The most celebrated of the poison-trees is the Upas, which grows in several tropical countries, but chiefly in the island of Java. The accounts given of the Machineel tree are nothing compared to the wonderful stories told of the Upas. No plant, not even grass, will grow under one of these trees, or anywhere near it. A drop of water falling from a leaf on any one beneath it, will produce inflammation. Whoever walks under one of these trees bare-headed, must expect to lose all his hair. To stay under it for a short time will cause sickness. To sleep under it is certain death. Birds fly over the tree with great difficulty, and if one should chance to alight upon it, woe be to him! Instantly he drops down dead. The wild beasts know the fatal tree, and shun it, but, if one venture beneath its shadow, he never comes forth again, but leaves his bones there. These stories which the natives really believe, they told to travelers, and, for a long time they were supposed to be true. One thing which caused these accounts to be so readily credited was the condition of things in a valley in Java, where these trees were found in abundance. The natives of Java told the Europeans of a wonderful valley that they called the Valley of Death, because the air was so poisoned with the noxious vapors of the Upas trees that no animal ever went through the valley. It dropped dead before the short journey was completed, and the ground was strewn with the bones of creatures that had perished there. The natives were willing to conduct their visitors to a hill that overlooked this valley at a safe distance. When they arrived at this hill, there, sure enough, was the valley, Upas trees, dead grass, bones, and all, just as the savages had described it. This settled the matter for a great many years in regard to the death dealing Upas tree. Other travelers to Java, rode up this hill, looked at the Valley of Death, shuddered, and rode down again. At last there arrived on the hill-top a man who made up his mind he would ride _through_ this valley! And so he did! Everybody said he was going to his death, but he was resolved to solve the mystery of the valley. He rode into it, and through it, and back again, and came out alive and well! Nevertheless he found the skeletons of wild animals, and of birds strewn the whole length of the valley. It was a mystery, but it was all cleared up afterwards. The valley was fatal to all animals except man. But the Upas tree had nothing to do with it. The valley was filled with carbonic acid gas to the height of a couple of feet from the ground.