Page:Popular Science Monthly Volume 23.djvu/663

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INSECTS AND DISEASE.

as also its greater frequency in Siberia and Lapland, where insects of the mosquito tribe are the great pest of the traveler. In Lapland the popular belief was long ago universal that the disease was caused by a peculiar insect, which suddenly descended from the air, and as suddenly disappeared. In the London "Times" (1860) it is reported that four hundred persons lost their lives in the south of Russia and in the province of Kiev from the sting of a "venomous fly" imported from Asia, the same fly having made its appearance there on another occasion, sixty or seventy years before. Virchow, who has made malignant pustule a special study, says: "Most probably, insects with piercing probosces effect the inoculation, such as gadflies (Bremse); but flies which make no wound may also implant the poison on the skin by their soiled wings and feet." The bites of these same flies may be generally harmless; they have no venomous power of their own, but only convey poison from sources of infection to man and animals.

Furthermore, when it is remembered that disease-producing bacteric germs are so minute that a million may rest on the head of a pin, and that the smallest puncture of the finest needle-point (as in Pasteur's experiments with chicken-cholera), when charged with an atom of infecting matter, may be sufficient to infect the body with the septic matter, it scarcely seems possible to ignore any longer the punctures of mosquitoes and other proboscidian insects as possible sources of both infection and contagion. With our present knowledge of the "germ theory" one would hardly dare, even once, to plunge an inoculating needle into the blood of a yellow-fever or typhus-fever patient, whether living and comatose or recently dead, and then withdraw it and plunge it into his own blood or the blood of other persons, yet this is exactly what the mosquito is doing in nearly every yellow-fever epidemic, and what, perhaps, the flea is doing in the filthy jails and ships infested with typhus. In the yellow-fever instance, it is to be noted, also, that the spread of the disease ceases with frost; so also do the peregrinations of the mosquito.

In this paper, however, my chief design is to present what facts I may be able in support of the mosquital origin of malarial disease—in fact, of ague. And, while the data to be presented can not be held to prove the theory, they may go so far as to initiate and encourage experiments and observations by which the truth or fallacy of the views held may be demonstrated, which, either way, will be a step in the line of progress. It is scarcely necessary to premise that other—nay, all—insects that infest and wound the human body may share in the guilt that will here be charged, in particular, to the culex; and so, of course, other diseases than ague, yellow fever, etc., may possibly have a similar history. Be it noted en passant that, so far back as 1848, Dr. Josiah Nott, of Mobile, Alabama, published a lengthy essay on yellow fever, in which he maintained the insect origin of that disease, and also suggested the "mosquito of the lowlands"