Page:Popular Science Monthly Volume 29.djvu/443

Rh Professor de Candolle had published for Switzerland, North Germany, and Belgium. Brown eyes were more common among women than among men. From the fact that 56 per cent of the children of parents who were bi-colored (or one of whom had brown and the other blue eyes) had brown eyes, it appeared that eyes of that color were on the increase. The majority of wives had brown eyes. The average number of children of con-colored parents was 4·49, and that of bi-colored parents 4·03—contrary to Professor de Candolle's observations, which gave the larger number to bi-colored parents. It also appeared that 52*6 per cent of the children inherited the eyes of the father and 47·4 per cent those of the mother; of the sons, 51·8 per cent inherited the father's, and 48·2 per cent those of the mother, while the figures with regard to the daughters were respectively 53·5 and 46·5 per cent. These figures show that in Sweden the eyes are not predominantly inherited from the mother alone, and that the offspring of equally constituted parents should not be weaker than they. Children under ten years of age were excluded from the examinations, and blue-gray and gray eyes were classified as blue.

Causes of the Extinction of Species.—Professor A. S. Packard has published an article in the "American Naturalist" on some of the apparent causes of the "Geological Extinction of Species." He reviews at length the factors of changes of climate to which he ascribes the most extensive phenomena of the kind. In the palæozoic ages, the climate of the whole earth was nearly uniform, and species were very widely diffused. Upheavals of mountain-ranges and continental masses, taking place at different epochs, produced more or less marked differentiations and local conditions favorable to some species and unfavorable to others, with the result that some flourished while others declined and faded out. The glacial epoch, bringing great changes of climates, produced also many revolutions in the relations of species. Changes in altitudes, marked on the American Continent by the elevation of the Rocky Mountain and Andean districts to from five thousand to ten thousand feet, the workings of which are still going on to a certain extent, also materially affected those relations; and similar changes have occurred in the other quarters of the world. "The biological changes were not due to climatic and geological changes alone, but it should be borne in mind that the great changes, slowly induced, but not without striking final results, ending in the addition or loss of vast areas of land, induced extensive migrations, the incursions of prepotent types which exterminated the weaker. The reaction of one type of life upon another, the results of natural selection, were apparent all through; but these secondary factors were active both during periods of quiet and periods of change. . . . Local extinctions due to local changes of level; the formation of deserts, saline wastes, and volcanic eruptions and vast outpourings of lava, such as took place in Oregon and Idaho during the Tertiary, with submarine earthquakes causing the death of fishes on a vast scale, these are quite subordinate factors."

Toad-Lore.—Toads have much in common with frogs, but they are. hatched from spawn that is deposited in long strings, while frog-spawn is in masses, and they have no teeth. They are also marked by ugly warts, which give out an acrid but not poisonous juice. They have tongues whose motions, nearly as quick as lightning, the eye can not follow, and which sweep in the insects they catch with such speed that the victims "seem to melt into thin air" rather than to be caught and swallowed. They can climb plastered and whitewashed walls or flights of steps, and even into flower-pots whose outward sloping sides would seem to forbid such an achievement. They will eat nothing that is not in motion except their own skins, which, when they are cast off, they roll up and swallow. The muscles of their thighs and legs strikingly resemble those of man. They can not breathe when their mouth is held open. The old necromancers used them freely and in various ways in their magic. In some parts of England the application of a toad is supposed to stop bleeding, and dried specimens are worn as charms against rheumatism. The members of a Devonshire family had a reputation for curing "king's