Page:Popular Science Monthly Volume 12.djvu/685

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growth is wonderful. Saplings fifty feet high, and but ten years old, are not remarkable. It is declared that seed sown in Jamaica at an elevation of 5,000 feet, in 1870, had in 1876 attained a growth of fifty feet. We have with our own eyes witnessed throughout an entire summer a growth of an inch a day. No one understood so well as Baron von Müller the nature and capacities of the Eucalyptus. He more than all others has made the world acquainted with it. With him was a scientific faith that this was the world's tree of promise. In this tree of Australia he saw the means with which to obliterate from the hydrographic map the rainless zones, to clothe with wood the desolate ranges of Tunis, Algeria, and Morocco, and render habitable parts of the Great Sahara, by indefinitely expanding the oases, to restore fertility to the Holy Land, to give rain to the Asiatic plateau, or the desert of Atacama, and furnish timber and fuel to Natal and La Plata.

None better than the baron, however, knew that, while able to stand great heat, these rapidly-growing eucalypti cannot resist great cold, and without these home conditions we must not expect of them their home achievements. Even at home the tribe does its best with its semi-tropical members. And there is a great range of variety until we meet even the Alpine species, of slow growth and very modest altitude. Skill and patience may do much; but in our country, except in a few favored spots, little can be hoped of the semi-tropical varieties north of latitude 30°, until acclimatization shall have been effected.

But it is claimed for the eucalypts that their presence is hygienic, or sanatory, especially in malarial regions. That the E. globulus has earned by fair experiment its name of fever-tree, as a preventive, seems now to be settled. Its rapid growth must make it a great drainer of wet soils, while its marked terebinthine odor may have its influence, and it is highly probable that the liberation of this essence into the air stands connected with its generation of ozone. But, whatever the sanatory activities of the eucalypt may be, the fact is squarely settled that spots in Italy, uninhabitable because of malarial fever, have been rendered tolerable by the planting of E. globulus, and it is believed that a more plentiful planting would nearly if not quite remove the difficulty. A military post is mentioned in Algeria, in which the garrison had to be changed every five days, such was the virulence of the malaria. A plantation of eucalypts cleared the miasma nearly away, and rendered unnecessary the frequent changes of the garrison. In this case 60,000 trees were planted.

But the eucalyptus has not a few medicinal virtues. Its oils and essences are antiseptic. Diffused in the sick-room, they purify the air and generate ozone. Already they have taken their places in the materia medica as very important internal medicines. The leaves contain the essence eucalyptol, and a resinous solid containing a bitter principle not yet understood, and which seems to afford the antifebrile