t we have been liberated from the paludal idea, and furthermore, that
we have learned that it is often better, instead of trying to prevent the
importation, for the most part imaginary, of malaria from distant marshes,
to suppress its production in the soil under our feet or in that
immediately surrounding us. We owe to it the knowledge, which we now have,
that malaria rises up into the atmosphere only to a limited height, so
that by placing ourselves a little above this limit in order to eliminate
the possibility of the malaria being carried up to us by oblique
atmospheric currents, we are enabled to breathe an air which does not
contain this ferment, or which contains it only in insignificant amounts;
thus one may even sleep in the open air during the night in very unhealthy
districts without running any risks. The knowledge of this fact has led
some peoples of Greece, and the inhabitants of the Pontine Marshes, to
sleep in the open air on platforms raised on poles four or five meters
(twelve to fifteen feet) in height. Some people in the Roman Campagna have
built houses for themselves on top of the ancient tombs, the walls of
which are perpendicular; the American Indians fasten their hammocks as
high up as possible to the trees of the malarious forests; and very
recently, the engineers of the Panama Railroad had little wooden huts
built in the trees in order to procure safety against the terrible
outbreak of malaria which occurred during the construction of that iron
way. We owe, finally, to this popular experience the discovery of the
specific action of quinine, and the consequent preservation of thousands
and thousands of human lives. Why should we reject _a priori_ and without
investigation other useful data which it may yet present to our
consideration? If we wish to make progress in this question of rendering
malarious countries healthy, we must always hold before our eyes a double
object--to find a means of prophylaxis which may be accessible to
everybody; and, at the same time, to find a means equally within
everybody's reach, to overcome chronic malarial poisoning and its evil
consequences. Science is still too far behind to permit us to hope that we
shall soon succeed in discovering this second means by purely scientific
researches. We ought, therefore, to gather together with great care all
the facts which point to the possibility of a solution of this problem,
and if the measures to which these facts point se