I cannot explain to you in this place how this gas is formed by plants. It would be a good plan for you to study up this subject, for it is quite curious, and very interesting. The gas is fatal to animal life. Neither man, beast, or bird can breathe it for even a short time and live. But the gas is heavier than the common air, and sinks in it. In this valley, as I have said, it extended only about two feet above the ground, and a man’s lungs were above it, so he could not inhale it. On horseback of course he was far above it. But low animals, and birds that alighted on the ground at once fell victims to it. This led to an examination of the Upas tree stories, and most of them were found to be fables. Grass and flowers do grow around these trees in most places; birds sport upon their branches, and lizards run up and down unhurt; and it is possible to remain under them without injury of any kind. But it is true that the juice of the upas is a powerful poison. The savages use it as a weapon to kill their enemies in war, and to slay the wild beasts. They dip the points of their spears and arrows in the poisonous sap. An animal dies in five or six minutes after being struck with one of these poisoned weapons. They take great precautions in collecting the sap, so terrible is their fear of this tree. On some plants the blossoms are so small they can scarcely be seen by the naked eye, and on others they are of enormous proportions. An African flower, the Aristolochia, has a large and curiously shaped blossom. It is shaped like a helmet with flaring edges, and the opening is so large that it will admit the head of a man, and can be worn as a hat. The flowers of the Victoria Regia, which are shaped very much like those of our water lily, are a yard in circumference. But the giant of blossoms is the Rafflesia Arnoldi. This is a long name, but the flower can bear it very well. [Illustration: RAFFLESIA ARNOLDI.] It grows in the islands of Java and Sumatra, and the buds and blossoms seem to be pretty much all there is of the plant. And quite enough too. The full blown flower is a yard wide. Each of its five petals is a foot long, and they stand at about the distance of a foot from each other. In the centre there is a deep honey-cup, which is capable of holding a dozen pints of fluid. The whole weighs fifteen pounds. The central cup is violet and red, and the petals are of a brilliant orange color, so that it makes a gorgeous display indeed. But this flower, so magnificent in size and color, has such a disagreeable smell, that after having satisfied your curiosity by looking at its gigantic blossom, you will be glad to get away from its neighborhood.