rom below and from above;
that is to say, to drain the subsoil, and at the same time increase the
evaporation of water from the surface of the ground. It is well known that
clearing off the forests of malarious countries has often proved an
excellent means of making lands salubrious which were before too damp;
for, by removing every obstacle to the direct action of the sun's rays
upon the ground, we cause an increase of evaporation from its surface, and
may thus be enabled to exhaust the superficial strata completely of their
water during the hot season. In very moist lands, which lend themselves
readily to deep drainage, the combination of the latter with a clearing
of the surface has, in almost every quarter of the globe, rendered
possible a very widespread and sometimes a quite lasting freedom from
malaria. But, although a nearly universal experience proclaims this fact,
there is a school which, following in the footsteps of Lancisi, maintains
the contrary opinion, that it is necessary to preserve the forests in
malarious districts, and even to increase their extent, since the trees
filter the infected atmosphere and arrest the malaria in their foliage.
This strange theory was formulated by Lancisi in 1714, on the occasion of
the proposed clearing of a forest belonging to the Caetani family, and
lying between the Pontine Marshes and the district of Cistema. Lancisi was
completely imbued with the paludal notion, and consequently believed that
the very severe malaria of Cistema was brought by the winds from the coast
marshes, instead of being produced in the soil surrounding the district,
which was then covered by this forest. He believed then that the forest
acted as a protective rampart, and he prevented its being cut down. But
toward the middle of the present century the Caetani had the woods cleared
off from the entire belt of land surrounding Cistema. Twenty years later I
was able to show that Cistema had gained greatly in salubrity. I published
my observation in 1879, and, naturally, was taken to task rather sharply
in the name of the sacred tradition. Happily these recriminations led our
Minister of Agriculture to have the question studied by a special
commission. This commission, after a conscientious examination extending
over three years of all the malarious localities in the province of Rome,
has just published its report,[1] the conclusions of which are entirely in
accord with the facts of universal experience