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Page:Popular Science Monthly Volume 20.djvu/66

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are not definitely contradicted by anything that we know, but are as yet still further from being fully sustained by facts; and they all prove to be beset by difficulties when they are subjected to a critical analysis. Thus, "it must be admitted that we do not at present appear to have the means for framing a complete and consistent theory of volcanic action, but we may hopefully look forward to the time when further observation and experiment shall have removed many of the existing difficulties which beset the question, and when by the light of such future researches untenable hypotheses shall be eliminated and the just ones proved and established."

Modern speculation, recognizing that the worlds of our system are bound by the same laws and had the same origin, now tends to look to the study of what is going on in the sun and planets as a valuable aid in ascertaining the reason of the operations to which our planet is and has been subjected.



"Dangers we can not avoid we must learn to defy."—Lessing.

CREATURES in a state of nature can almost dispense with sanitary precautions; Providence has secured their safety in that respect. Animals are born with the instinct that enables them to distinguish wholesome from injurious plants. In the wilderness, where the neighborhood of man does not tempt them to brave the winter of the higher latitudes, most birds emigrate in time to avoid its rigors; those that stay can rely on their feather-coats; natural selection has adapted their utmost power of endurance to the possible extremes of the atmospheric vicissitudes. The sexual instinct of wild animals is limited to certain seasons and months that preclude the possibility of their young being born at any but the most favorable time of the year. From birth to death the children of Nature can trust themselves to the guidance of their hereditary inclinations; all the contingencies of their simple lives have been amply provided for.

These provisions do not apply exclusively to a state of affairs which the agency of man has in so many ways modified or even reversed; still, it would seem as if Nature had failed to make adequate allowance for the possibility of certain perils incident to our artificial mode of life. This fact is perhaps most strikingly illustrated by the treacherous non-repulsiveness of certain mineral poisons. The offensive taste of poisonous plants seems to be proportioned to the degree of their noxiousness; hemlock, strychnine, and opium are forbiddingly