Page:Popular Science Monthly Volume 20.djvu/261

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249
DISEASE-GERMS.

An epizoötic malady extensively prevails on the Continent of Europe, though fortunately but little known in this country, which is sometimes designated "splenic fever," and sometimes "anthrax" or "carbuncular" disease, while it is known in France as "charbon" or "pustule maligne." In its most malignant form, it causes the death of the horses, cattle, and sheep affected by it, in the course of four-and-twenty hours. In the less severe form of anthrax disease, it occasions great and prolonged suffering, even when final recovery takes place. Both forms seem propagable to man. Between the years 1867 and 1870, above 56,000 deaths from this disease are recorded as having occurred among horses, cattle, and sheep, and 528 deaths among the human population, in the single district of Novgorod in Russia. It appears to be scarcely ever absent from France, and is estimated to involve an annual loss of many millions of francs on the part of breeders in that country, whole flocks and herds being carried off at once, and their proprietors ruined. A mild epizoötic of this type seems to have prevailed in this country between 1850 and 1860; while the "plague of boils," under which many of our human population (my unhappy self among the rest) suffered during some part of that decennium, was probably brought on us by infection from animals. Attention has lately been drawn to a severe and often fatal malady occurring among the "wool-sorters" at Bradford, which is pretty certainly a modification of "splenic fever," communicated by the wool of sheep infected with that disease.

As far back as 1850 it was observed by two distinguished French pathologists, MM. Bayer and Davaine, that the blood of animals affected with splenic fever contained minute, transparent rods; but their fungoid nature and life-history were first worked-out a few years since by a young German physician named Koch, whose account of it was soon confirmed by Cohn, the eminent Botanical Professor of Breslau, and afterward in this country by Mr. Ewart, all of whom "cultivated" the plant in aqueous humor, or some other organic liquid of suitable character, kept at nearly blood-heat. They found the "rods" to be produced by progressive extension from germ-particles of extreme minuteness. At first they are simple tubes divided at intervals by transverse partitions, but after a time minute dots are seen within these tubes, which gradually enlarge into ovoid bodies that lie in rows within the rods, and at last the rods fall to pieces, liberating the germ-particles they included. The minutest drop of the fluid containing these germs, if conveyed into another portion of cultivated fluid, initiates the same process of growth and reproduction, and this may be repeated many times without any impairment of the potency of the germs, which, when introduced by inoculation into the bodies of rabbits, Guinea-pigs, and mice, develop in them all the characteristic phenomena of splenic fever. Koch further ascertained that the blood of animals that succumbed to this disease might be dried and kept for