Page:Popular Science Monthly Volume 52.djvu/297

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FRAGMENTS OF SCIENCE.

borne upon the legs (insects) or the tail; that they may be deeply sunk in the body and yet have no inlets for the vibrations of the sonorous medium (many aquatic animals). It is well that we should know of animals with two tails or with two bodies permanently united; of other animals developed within a larva which lives for a considerable time after the adult has detached itself (some starfishes and nemertines); of animals which lay two or three kinds of eggs; of eggs which produce two (an earthworm) or even eight embryos apiece; of males which live parasitically on the female, or even undergo their transformations, as many as eighteen at a time, in her gullet; and of female animals which are mere bags of eggs. The more the naturalist knows of such strange deviations from the familiar course of things the better will he be prepared to reason about what he sees, and the safer will he be against the perversions of hasty conjecture.

The Life of the Toad.—From a study of the toad, by Mr. A. H. Kirkland, we learn that in this region it usually emerges from its hibernating quarters during April. Cold weather retards its movements, but on warm days in the spring the toads make their way to the ponds and stagnant pools. Mating is begun as soon as the water is reached, or even before, and in a few days the long slimy "ropes" of eggs deposited by the female may be found in the pools. The eggs are nearly black, and rapidly increase in size. In two weeks the young tadpoles are clearly outlined, and in three or four weeks the eggs hatch. The vegetable detritus of the pond bottoms and the slime and algæ attached to sticks, planks, etc., seem to be the common food of the tadpole. Warm weather favors the growth of the tadpoles, and usually the young toads are fully developed, leave the water, and spread over the fields. At this stage they are extremely sensitive to heat, and secrete themselves under leaves, stones, rubbish, etc., during the day; but after a hard shower they come out by thousands. Observations of the toad's feeding show that eleven per cent of its food is composed of insects and spiders beneficial or indirectly helpful to man, and eighty per cent of insects and other animals directly injurious to cultivated crops or in other ways obnoxious to man. Their stomachs can accommodate enormous quantities of food, and one will consume in twenty-four hours an amount equal to that required to fill the stomach four times. It is estimated that in one season a toad might destroy cutworms which would otherwise have damaged crops to the extent of $19.88. The toad thus renders conspicuous service to farmers, and gardeners and greenhouse owners could make it of special use. As there are laws for the protection of insectivorous birds, why should there not be as stringent legislation against the destruction of toads? If merit of service rendered to man be the standard by which legislation is determined, the toad presents a record which will compare favorably with that of any insectivorous bird.

Magnitude of Mexican Ruins.—Of the ruins of ancient cities in Mexico which Mr. W. H. Holmes has examined and described in his publications respecting them in a comprehensive scientific manner, none, perhaps, are more remarkable and extensive as a whole than those near the city of Oaxaca. Many of the important works here are found on mountain tops, "and one soon comes to recognize the notched profiles of the ridges and peaks that border the valley as being due to the strangely directed enterprise of the ancient inhabitants. The feeling of surprise induced by this discovery is followed by one of amazement as the real nature of the work dawns upon the mind. As the explorer climbs the slopes and picks his way from summit to summit, he is fairly dazed by the vast array of pyramids and terraces, which not only crown the heights, but overspread the steep slopes, destroying traces of natural contour and making the mountains actual works of art." Climbing one of the larger pyramids of the group on the summit of Monte Alban, the author obtained a magnificent panorama of the mountain and the surrounding valleys and ranges. "Turning to the north, the view along the crest was bewildering in the extreme. The crest of Alban, one fourth of a mile wide and extending nearly a mile to the north, lay spread out at my feet. The surface was not covered with scattered and obscure piles of ruins, as I had expected, but the whole mountain had