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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    which surrounds the Cisterna country on the south. This wood is that of which Lancisi prevented the felling in 1714, being persuaded that woods ameliorated the air of marshes, and in this case protected Cisterna from the south wind which he believed conveyed the malaria. On the contrary, the destruction of this great wood has pro- cured for Cisterna a marked increase of salubrity and population * In spite of this, the explanation is fallacious. The existence of decomposing vegetable detritus in a forest is not sufficient of itself to cause malaria, as we see in other parts of the globe vast forests, containing such detritus, which are, notwithstanding, salubrious, as, for example, some virgin forests of South America. It is, however, certain that when woods cover malarious lands, they may favour its production, especially if situated at a level which hinders the outflow of water. The wood, intercepting the sun's rays, impedes evaporation and allows the malarious soil to retain much moisture during the hot season, even in the strata most exposed to the action of the atmosphere. This obstacle being removed, the consequent summer de- siccation markedly diminishes the malaria production, and if the soil be not deep may go so far as to arrest it. One can under- stand, therefore, how disafforesting alone may increase the salu- brity of such places, and how, on the other hand, in deep soils, it cannot arrest malaria without the help of such drainage as may exhaust the water of lower strata which the sun's rays are not able to dry. It is the opinion of many that malaria may be generated by the decomposition of low organisms, animal and vegetable, which die in large numbers when sea water is mixed with fresh water, collected in its vicinity. This opinion is based on the coinci- dence that in some parts of the Italian coasts where fresh water ponds are only separated from the sea by dunes, intermittent fevers occur. This has, however, only been met with where the surrounding lands are malarious ; or were so formerly, and appear still capable of becoming such again, whenever the old marsh cuora which they contain are placed, in summer, under favourable conditions * Lancisi, Unedited Addresses on the Cutting of the Woods of Cisterna and Semoneta.