Sumatra is also a possession of the Dutch East Indies, but it is not very important as compared with Java. Although it is three times as large as Java, it has scarcely one-tenth the population. There is a pretty good reason for this. In the first place, the mountainous region is very rugged and much of it is covered with jungle; therefore, it is neither habitable nor productive for mankind. In the second place, the broad plain on the east side of the island is not well adapted to cultivation; it is cut by deep river valleys in the higher parts, swampy in the middle part, and covered with water next the coast during a part of the year. Rather singularly the lakes--and there are many--are not in the low, swampy lands; most of them are high in the mountains. What is still more singular, these lakes are the craters of inactive volcanoes. But Sumatra, like Java, has many active volcanoes. One of these, Dempo, is almost constantly active. Every now and then it discharges great quantities of sulphur gases; these are caught by the rain and, falling on the cultivated lands, kill pretty nearly everything touched. In the jungles nature has been very lavish with life. The forests contain more than four hundred kinds of trees--among them teak, ebony, camphor, and even good pine. Sumatra is also the home of several trees and plants from which gutta-percha is obtained. Railroads to connect the forest belts to the coast are the one thing needed to make Sumatra a lumber-producing country. For some reason or other many of the wild animals that crossed the shallow water between the Malay Peninsula and Sumatra did not cross the Sunda Strait to Java. There are many more kinds of animals in Sumatra than in Java; indeed, nearly all the larger species of wild animals of southern Asia are found in Sumatra, and only a few are in Java. There are many elephants in the uplands; the rhinoceros lives in the lowlands; the tiger lives in the jungle, as in India. The flying "fox" is one of the curiosities of Sumatra. So much for a name, however, for the animal is not a fox but a very large bat. Its wings are membranes that connect the limbs corresponding to one's fingers. Like other bats, it hangs from the limb of a tree, head down, in the daytime, and goes to business at night. Its body is not much larger than that of a hare, but when in flight it is four or five feet from tip to tip. [Illustration: Natives in the jungle, Sumatra] The flying "cat" is likewise a misnamed animal that bears no relationship to pussy, but is a kind of lemur. The wild dog, however, is very much dog and nuisance at the same time--as much of a nuisance as the coyote of the western United States, and far more numerous. The "coffee" rat is likewise a great nuisance wherever found; unfortunately it is found almost everywhere. Monkeys are also numerous.