Page:Popular Science Monthly Volume 24.djvu/733

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young children at this festive season over-fed and with a short allowance of sleep, are common instances of the victims of 'cold.' Luxury is favorable to chill-taking; very hot rooms, soft chairs, feather beds, create a sensitiveness that leads to catarrhs. It is not, after all, the 'cold' that is so much to be feared as the antecedent conditions that give the attack a chance of doing harm. Some of the worst 4 colds happen to those who do not leave their house or even their bed, and those who are most invulnerable are often those who are most exposed to changes of temperature, and who by good sleep, cold bathing, and regular habits, preserve the tone of their nervous system and circulation. Probably many chills are contracted at night or at the fag-end of the day, when tired people get the equilibrium of their circulation disturbed by either over-heated sitting-rooms or underheated bed-rooms and beds. This is especially the case with elderly people. In such cases the mischief is not always done instantaneously, or in a single night. It often takes place insidiously, extending over days or even weeks. It thus appears that 'taking cold' is not by any means a simple result of a lower temperature, but depends largely on personal conditions and habits, affecting especially the nervous and muscular energy of the body."

How and where Malaria thrives.—The health-officers of New Britain, Connecticut, have made an instructive report concerning the prevalence of malarial diseases in that town, and their connection with certain supposed causes. The causes of malarial and other miasmatic diseases are not identical, though they are similar, and the two classes not infrequently occur in a given locality at the same time; and the hygienic measures required to prevent them all are the same. The essential conditions for the development of malaria appear to be: the presence of the malarial germ; a high temperature and dry atmosphere; and favorable conditions of the soil; and the absence of either of them will suspend or prevent the action of the poison. We have power only over the third condition. "A generous rain in the vicinity has, we think, invariably suspended its action. And yet a previous condition of moisture is essential to its manifestation. All deposits of vegetable matter, such as muck, sink-drainage, heaps of decaying vegetable matter, or even wet, spongy land, furnish the essentials for its support; but it is requisite that the soil shall have been very wet, or covered with water some portions of the year." A generous crop of grass, and perhaps of other vegetable substance, has been known to prevent malaria. In 1880 nearly all the families in the neighborhood of some lots which were largely a deposit of muck had malaria. The lots were plowed, dragged, and sowed with grass-seed, and the appearance of the crop of grass and weeds was attended by a disappearance of chills and fever. Two or three other instances are mentioned in the same town, in which fever-and-ague was banished by giving a similar treatment to tracts of swampy and mucky soil. Another case is specified where malaria was prevented by the drying up of the sewerage and sink-water which usually found its outlet through a system of ditches cut in muck. Preparations were making to lay tiles in the ditches and fill them up, but, before this was done, a heavy rain washed them out, and "caused the prevailing sickness to abate as suddenly as it had commenced." From the first, malaria has not prevailed in those parts of the city where vegetable deposits and filth have been absent, and the health of the streets in which sewers have been laid has been remarkably good.

Can Dogs be taught to read?—Under the title "Instinct," Sir John Lubbock writes as follows in a recent number of the "Spectator":

"Sir: Mr. Darwin's 'Notes on Instinct,' recently published by my friend Mr. Romanes, have again called attention to the interesting subject of instinct in animals. Miss Martineau once remarked that, considering how long we have lived in close association with animals, it is astonishing how little we know about them, and especially about their mental condition. This applies with especial force to our domestic animals, and above all, of course, to dogs. I believe that it arises very much from the fact that hitherto we have tried to teach animals, rather than to learn from them—