Page:Popular Science Monthly Volume 32.djvu/737

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been upheaved. The natives wash this earth slowly away by hydraulic mining. The third system of mining is by sinking pits in the lower or plain parts of the valley, and washing the earth extracted by band.


Effects of an Earthquake.—A paper was read in the British Association by Dr. T. Sterry Hunt and Mr. J. Douglas, describing their observations of the effects of an earthquake which took place in Sonora, Mexico, on May 3, 1887. The authors found the results of the undulatory movements of the soil apparent in the San Pedro and Sulphur Spring Valleys in great numbers of cracks and dislocations. For distances of several hundred feet, sometimes with a generally north and south course, vertical down-throws on one side of from one foot to two feet were seen, the depressed portion rising either gradually or by a vertical step to the original level. Branching, and in some cases intersecting, cracks were observed. These depressions were evidently connected with outbursts of sand and water, which, along cracks—marked by depressions on both sides—sometimes covered areas of many hundred square feet with layers a foot or more in depth, marked here and there by craters, two feet in diameter, through which water had risen during the outburst of these volcanoes.


Agassiz's Service to Evolution.—Professor Le Conte's ascription to Professor Agassiz of the credit of having laid the basis for the doctrine of evolution is confirmed, from a different point of view, by Professor Alfred Newton, in his opening address before the Section of Biology of the British Association. The speaker, referring to Agassiz's doctrine of centers of creation, said that "creation in his mind was no figurative expression. lie meant by it. . . a direct act of God—in other words, his belief was, that there had been going on around us a series of mysterious performances, not one of which had ever been consciously witnessed by a human eye, each of which had for its object the independent formation of a new living being, animal or plant." This doctrine of a continuous series of miraculous acts having gone on for an indefinite time was perfectly logical when the premises were admitted; and it became obvious that the alternative was between that doctrine and the theory of transmutation of species. The having made this thought clear is declared by Professor Newton to have been a great service rendered to the new theory by one who was its most determined opponent.


A Floral Moth-Trap.—Mr. Robert E. C. Stearns, in the "American Naturalist," describes the plant Araujia albens as a "mothtrap." The plant, formerly called Physianthus, is a native of Buenos Ayres, but has been pretty widely distributed in the United States, and may be found now at places as far apart as Boston and San Francisco. The insects are caught in the flower, which is trumpet-shaped, flaring at the mouth, where the petals divide, and then uniting and forming a tube, which is swollen into a bulbous form where the corolla joins the calyx. The stamens are furnished with side wing-like processes and exterior spurs, which press against the gymnecium, and hide the ovaries and pollen-masses. "The moth, in pursuit of the nectar, first reaches that portion contained in the pockets between the bases of the spurs; then, in search of more, having already thrust the proboscis down the tube of the flower, describing a curve between the exterior of the stamineal crown or mass and the inside of the bulb of the perigonium, it has to push the proboscis upward in order to reach that portion of the flower where the anther-cells, pollen-masses, and glands are in close juxtaposition." Having satisfied its hunger, or otherwise, upon attempting to withdraw the proboscis by a direct pull—which it can not do, because the organ is not provided with any muscular arrangement by which the curved motion made in entering can be reversed—the proboscis "becomes wedged in between the edges of what may be termed the anther-wings, or rather the edges thereof, and is held tight, very much in the same way that an old-fashioned boot-jack grips a boot. The more the moth pulls, the tighter or firmer the grip, and escape is impossible, unless the flower has reached such a degree of maturity that its substance has become somewhat softened or wilted."