Selected monographs.

New Sydenham Society

Date:: 1888

Credit: Selected monographs. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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$♦ necessary to separate from this material the true excitor of disease. Assuming that this infection, like some others of which the etiology is now well known, may be due to animal parasites, its isolation becomes possible. In this material it is presumable that, besides the true excitors of the disease, there are other substances which do not contribute to this result. There may be living organisms or inorganic matter. We are not concerned with the latter, whose development should encounter more difficulty as conditions are supplied favouring the growth of the former. We know the three condi- tions (Chapter I.) experience has shown to be indispensable to malaria development. We reproduced these conditions in the following way. In a large well-ventilated air bath were placed on wooden shelves, above a layer of sand heated by gas, some large flat capsules of porcelain. Some of these were filled to the height of 5 cm. with earth kept constantly wet. Others contained a layer of water, renewed as it evaporated, and within which were placed some small tin boxes full of earth. The sides of these were perforated a little way from the bottom, so as to allow the water to penetrate and keep constantly moist the lower strata of the earth. Thermometers were placed so as to show the tem- perature of the air and earth, and during the entire day a temperature of 30°—35° C. was kept up. In the evening the gas was extinguished, and the air bath and earth in the boxes remained at the same temperature as the air of the laboratory. In this way we reproduced, in these artificial marshes, similar to those of the Campagna, all the conditions of temperature, moisture, and access of air which are found in malarious lands at the time of their greatest activity. The most notable result was that almost immediately a large number of the organisms in the earth and mud died. The development of diatoms and desmidege and also of hypomycetse was suspended. Moulds ceased to form on the surface of the earth and vases, the phenomena of putrefaction were arrested in the marsh mud, whilst they attained a high degree when this was kept under a bell-glass. The elimination of a great part of the organisms in the crude material rendered easy the search for those which are concerned in causing malaria. In this we era- ployed the method devised by one of us (Klebs)—called by him fractional cultivation, afterwards adopted by Pasteur, and by$

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