Page:Popular Science Monthly Volume 21.djvu/295

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that lie partly outside of the epidermis enjoy the least protection, as in certain ferns, while a higher degree of protection is given when the cells are sunk beneath the epidermis and framed in a kind of funnel; and the highest degree when the stomata are arranged in rings or ovals on the under-side of a rolled leaf. Another means of protection is afforded by the structure of the epidermis, which is fortified by a strong cuticular structure, hardly permeable to vapor in many Australian plants, and is sometimes re-enforced by deposits of oxalate of lime. Such structures are peculiar to plants which have to sustain great drought. The epidermis of many plants, as the Eucalyptus globulus, is also covered with a coating of wax, which serves not only to protect it, but also to give a deeper setting to the pores. The protective effect of hairs operates in several ways: they cover the pores; they form a kind of space over the pores in which air and vapor may collect; and they constitute a kind of screen over the whole body of epidermis-cells against insolation and desiccation. Thus, plants growing on high, dry mountains, or in the steppes, are generally thickly haired. Hairs also serve to make the plant measurably defiant of sudden changes of temperature, and form an important part of the vegetable economy of regions like Soodan and continental Australia, which are subject to such changes. Even in temperate climates, varieties of the same species growing in open and exposed places are more hairy than those growing in protected woods. In the eucalyptuses the intercellular spaces and air-passages of plants growing in dry situations are much contracted, while in those growing in valleys and along rivers they are expanded. Willkomm has called attention to the fact that a sap strong in saline solutions is much less subject to evaporation than a thinner sap; and thus the halophytes keep fresh in stony places and the driest climates, while the Chenopodiaceæ (goose-foots), with much salt in their juices, flourish in dry places, and are met abundantly in the Asiatic steppes and the interior of Australia; and these look green and vigorous in the driest time of the year, when everything else is parched and brown. The form and position of the leaf also often show an adaptation to help the plant resist drought. Plants having to grow in a dry climate generally exchange the usual broad leaves for a narrow, close one, have it reduced to a cylindrical form, or, as in the brooms, make a green limb serve them as the assimilating organ. Broad leaves are seldom found in very dry regions. Many species peculiar to hot and dry situations have a faculty of arranging their leaves vertically, so that only the edge is exposed. The Lactuca scariola, the only European plant having this peculiarity, grows on roadsides and dry hills, while all the other species of lettuce, growing in shady and moist places, and in gardens, have the leaves arranged in the ordinary way, except that Lactuca sativa puts out vertical leaves when it is growing in a thin soil. The ethereal oils and thorns of plants may also possibly serve some protective purpose, but this is a subject for further investigation.


Terra del Fuegians in Paris.—Eleven natives of Terra del Fuego, four men, four women, and three children, were taken to Europe by 31. Waalen, who has resided for several years at Punta Arenas, Patagonia, and have been entertained at the Jardin d'Acclimatation in Paris. M. Waalen was fishing for seals in the waters of their inhospitable island when he came in contact with these savages, and succeeded, by giving them plenty to eat and treating them with tact, in getting them to stay on his vessel, whence they were transferred to a Hamburg steamer on its way to Europe, M. Waalen depositing security with the governor of Punta Arenas for their safe return after making their European tour. What mark their visit will make upon them, and how long it will endure, is a question which the experiment of Captain Fitzroy may help to answer. He took back three Fuegians, two men and a woman, after they had been three years in Europe, and had seemed to become nearly civilized, and set them among their tribe, in a good house, with a tract of tillable land, tools, and a missionary to take care of them. Going back to see them a few months afterward, he found all that pertained to civilization destroyed, that they had returned to complete savagery, and that the missionary was