But there is a tree that produces sugar ready-made. This is the manna tree of Sicily. The sap hardens on the trunk and branches into sugary particles, which are scraped off with wooden knives. This kind of sugar is used principally in medicine. It is insipid in taste. A species of Laurel in India contains camphor in all its juices. Break up twigs, stems, and leaves of this tree, and heat them, and the liquid that comes from them will soon condense into camphor gum. The seeds of one kind of palm produce a fine oil; and the stalks of another give us wax, of which candles are made. This wax forms on the outside of the stalk, at the places where the leaves join the stem. From another palm is extracted a juice that when exposed to the air for a short time, becomes wine. In arid deserts, and in unwholesome marshes plants flourish luxuriantly, the leaves of which contain pure, sweet, freshwater, always ready for the thirsty traveler. So far we have only spoken of the wholesome juices of plants and trees, but a large number are full of deadly poisons. Many of these grow in our own woods and fields. Some of the poisons have been utilized in medicines, for it has been found that, properly prepared, and given in small quantities, they can frequently arrest disease. Such is opium, which we get from the poppy, strychnine, and prussic acid. All of these are terrible poisons, but when administered by a physician in small doses, they relieve pain, and help to cure disease. Other vegetable poisons seem to be only destructive. If a man should, ignorantly take refuge under a Machineel tree from a shower, and remain there for any length of time after the rain began to drip upon him, he would suddenly discover that blisters were breaking out on his skin, and that sharp pains were running through his limbs, and he might well feel thankful if he escaped without a fit of sickness. This, at least is the story that the savages tell who live in the regions where the Machineel grows. It is probable that they exaggerate the facts, but they will none of them go near a tree of this species if they can help it; and there is no doubt that it is very poisonous. [Illustration: THE DEADLY UPAS.]