Selected Monographs.

  • New Sydenham Society.
Date:
1888
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Licence: Public Domain Mark

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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    of originating this poison. The cause is simply reduced to impotence; but examples are not rare in which, after this has happened, the development has recommenced and attained large proportions when the external conditions, which had been banished, were reproduced. In a district long free from malaria, neglect of the water scheme, inundations, or superabundance of rain, or accidental opening up to the air of some of the old foci, suffices to start the malaria again. The conversion of the Crown domains of the Val di Chiana into private property has led, in a great part of the valley, to neglect of the hydraulic works, allowing a return to the former state, and consequent reappearance of malaria in many places in which there had long been no trace of it. It is this which has happened in the Agro Eomano, which in the imperial epoch had been rendered so healthy as to permit of a summer residence in villas situated in spots now regarded as amongst the most insalubrious in the temperate zone, showing that not even centuries of exemption can ensure that the cause has been got rid of, beyond the possibility of recurrence. This remarkable tendency of malarious lands has stimulated research as to the nature of the agent that produces this effect, in the hope that, this being once known, means might be discovered of destroying it and rendering its development impossible, and thus obtaining a lasting and secure amelioration. The first researches were directed to the examination of the gases diffused in the soil for one capable of generating it, but with only negative results. Again, the supposition that some volatile product of animal or vegetable decomposition might be the cause has not been borne out by facts. It has never been shown that the mud and air of marshes contain an inorganic substance capable of developing, without the intervention of any other substance, malarious fever. Moreover, its production, even in marshy lands, is sometimes wanting, although animal and vegetable organisms undergo putrefaction as actively as in those which are malarious; while, on the other hand, malaria may develop in non-marshy lands in which such putrefaction does not occur. The want of exact correspondence between the quality of the soil and the production of malaria has led some to suppose that such may not be due to a specific cause, but rather the result of