Page:Science vol. 5.djvu/466

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��theory imicU more in delail, anil for the first time makes it complete. For this thorough- going treatment of the subject by the chief geologist, the excellent topographic and geo- logic work of Mr. Strong prepared the way.

Wiaconain is to be congratulated upon the successful completion of a work which in so many other states has had a different issue.

���When Baron Nordenskiold retired in April, 1882, fi-oni the presidency of the lioyal acad- emy of sciences at Stockholm, he look for the subject of his address the story of tbc Zetii brothers. This address was puhlislicd in Swedish in 18>43 : and in the same year he laid before the Congr^s des Ami^ricanistes, at their session at Copenhagen, three of the early maps, illustrative, as he thought, of an early acquaint- ance with Oi-eeuland, jiosterior to the so-called Northman discovery in the tenth century, and earlier than the period of Columbus. These were the Zeni map of 1380 (1390?) ; a map of 1427, found in a manusciipt of Ptolemy at Nancy ; and the Donis map of the edition of Ptolemy, printed at Ulm in 1482. In the Ger- man version of Nordenskiold's papers, which has recently appeared as ' Studien und forschun- gen, ' we have Ibis same Zeni study in a language easier read by most inquirers. Those who believe in the aubstsulial truth of the Zeni nar- rative will find Nordenskiold on their side. He identifies the Frisland of the story with the Faroe Islands, makes the Zeni to have reached Greenland, and identilies the Estoliland and Drc^eo of the Frisland liahennan with our American coast from Newfoundland south.

The botanical portion of the book has been contributed by three writers, — Nathorst, Kjell- man.and Wittrock, — who treat respectively of the former botanical geography of high lati- tudes us indicated by the results of polar re- search, the biology of the arctic flora, and the vegetable life of the naked snow and ice. All of these articles are remarkably free from tech- nicality, and form pleasant and instructive reading, the last being especially valuable be- cause of its full refereuces tc the literature of the subject.

Fossil collections ma<le fVom time to time in the arctic region, and, for the most part, elaborated by Beer, when compared among

Sttidlttt und fitrtcAuHgm trritnla^^t ilurck meinf rfiien irn

��themselves, and with similar collections ft Europe, show a remarkable uniforaiity ia the early flora of the entire northern part of the world, until, scattered and driven southward along numerous lines of migration, it has left its descendants mainly on the eastern sides of the two great continents, as Dr. Gray has already shown in bis history of Sequoia.

For the most part, the present arctic flora composed of the descendants of tertiary alpioe species, which, wandering fiom their original! homes. — the Alps, Che mountains of Greenland'' and Scandinavia, the Caucasus, and the Altai and Rocky mountains, — were driven back, st the end of the glacial period, to high elevations, or into the circumpolar region, by the warmer climate which succeeded. The collections made by the returning Vega party at Mogi, in Japan, are interesting because they indicate a certain, though relatively slight, reduction in tempera- ture in that part of Asia eorresiMnding to the glaciation of America and Euroiie, though, as is well known, no traces of inland ice occur there.

The arctic flora of to-day is a most interest- ing subject for study. While the ocean, at a short distance from shore, Bup[K>rts a grawth ot giant kelps and dark Florideae. which maoifeat continued activity the year through, vegetating in the short summer, and pushing their repro- ductive processes during the long winter night, the land-plants are all pygmies, apparently lesa because thej' cannot endure the intense cold of winter, than because they do not enjoy sufScieat warmth in summer to assimilate enough organic matter for any considerable growth,

In a region where the average daily temper* ature for the least colli month of summer ia bat a few degi'ees above the freezing-point, and. where vegetation is practically limited to about two months of even this slight warmth, iDtu«8t> ing adaptations are met with on every hand. Annuals are as good as unknown, the season proving too short for the development of their vegetative organs, and the subsequent matura* tion of fruit. The entire flora is practical!; biennial or perennial ; the plants rapidly push- ing into bloom, like our spring flora, willi the first abatement of the cold of winter, yet, an- like the latter, barely fruiting, and elaborating material for the nest year's flowers before tbn short summer is succeeded by another winter. Indeed, the season is too short for the m^ority of even these precocious and hardy plants, many of which are forced to rely on vegetative reproduction except in the most favored situ^ tions, while nearly all are caught in the n^dit of flowering by the cold of autumn, whidlj

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