Page:Popular Science Monthly Volume 37.djvu/521

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505
EVOLUTION AND DISTRIBUTION OF ANIMALS.

the sun. We have, says Prof. Vogel, to think of these two bodies as surrounded by extensive atmospheres, and that that of the principal body, or Algol itself especially, must possess considerable illuminating power. Under certain presuppositions, the height of this atmosphere is estimated at 216,000 English miles, and that of the atmosphere of its dark companion at 168,000 miles. The smallest interval between the atmospheres of the two bodies will thus be 1,600,000 English miles, or less than can be found in our solar system. It is not easy, as Prof. Vogel suggests, to conceive two bodies so near of nearly equal size, one of which is in the highest glow of heat, and the other in a condition of far-advanced cooling. But the facts of observation lead to this conclusion, and in science facts constitute the highest and ultimate authority, before which everything must yield. Thus, we learn from the remarkable discoveries in Potsdam and Cambridge that the world-order we meet in our solar system does not reign throughout the kingdom of the fixed stars, but that other relations come in which are quite different from those under which we live.—Translated for the Popular Science Monthly from Daheim.

 

EVOLUTION AND THE DISTRIBUTION OF ANIMALS.[1]
By DAVID STARR JORDAN,

PRESIDENT OF THE UNIVERSITY OF INDIANA.

II.

I was lately called to examine a specially interesting problem in geographical distribution, that of the dispersion of fishes in the Yellowstone Park. This region is a high volcanic plateau, formed by the filling of a mountain basin with a vast deposit of lava. The streams of the park are for the most part among the coldest and clearest of the Rocky Mountains, and apparently in every way suitable for the growth of trout. All the hot springs of the great Geyser basin are not sufficient to warm the waters of the Fire-hole River. Yet, with the exception of the Yellowstone itself, all these streams are destitute of fish-life. A reason for this is apparent in the fact that the plateau is fringed with cataracts which no fish can ascend. Each stream has a canon and waterfall near the point where it exchanges the hard bed of lava for the softer rock below. So the best of trout-streams, for an area of fifteen hundred square miles, are left without trout, because their natural inhabitants can not get to them.

On the theory that each species occupies those places best

  1. An address delivered before the Chicago Institute, in a course on the Testimony of Science in regard to Evolution.