There the water remains, out of the reach of sunbeams or wind, and if a traveller happens to be thirsty, all he has to do is to pierce the base of one of these gigantic leaves, and out rushes a stream of the purest water, as is shown in the illustration.
Next to the Traveller’s Tree is shown one of those extraordinary vegetables called Pitcher-plants, from the strange conformation of the leaves. They inhabit Borneo, Siam, and other hot countries. In these remarkable plants some of the leaves are developed into suitable pitchers, with hinged lids, exactly like our hot-water jugs. They serve, however, a different office, and contain cold water which the plant has distilled from the dew.
As the monkeys are in the habit of resorting to these plants when thirsty, they are sometimes called Monkey-pots. There is an admirable account of the Pitcher-plants and their development in the Transactions of the Linnæan Society, vol. xxii. part iv. The scientific name of those plants is Nepenthes.
Below the vegetable comes a rather celebrated animal cistern, namely, a portion of one of the stomachs of a Camel.
It exactly corresponds with that part of an ox which butchers call “honey-comb tripe,” and consists of a multitude of cells, which can be closed or opened at will. When the camel takes in its provision of water, it can treat this portion of the stomach much as the hive bee treats the honey-bag, and fill its cells with water.
By degrees, when it finds the necessity for moisture, it can squeeze the water out of these receptacles into the digestive portion of the interior, and so can sustain life for a wonderfully long time under conditions which would kill any other animal. I may remark, by the way, that the amount which a camel can drink, and the length of time through which it can endure its desert life, have been much exaggerated. There is another point to be considered, namely, the curious resemblance between these cells and the honey-comb of the hive bee. Every one knows that honey, no matter how tightly closed, will crystallize and lose its best qualities if kept in jars, whereas if it be allowed to remain in the waxen comb, where it is divided into very small portions, it will remain good for years.
It is just the same with the cells of the camel’s stomach, they being able to preserve water in a pure state by distributing it among a number of small cells, which can be opened or closed at will.
Then we come to the various means of obtaining water.
Reference has already been made to the Filter, by which foul water can be made pure for human consumption, and we will therefore pass to another mode of obtaining pure water, namely, the Still.
In former days, if there were a failure of the supply of fresh water on board ship, the whole of the occupants must necessarily perish. Now, however, no such danger exists, as every well-furnished ship carries at least one Still, by means of which the sea-water can be made to abandon its salt, and to give out nothing but pure water fit for drinking.