436 
The Water Economy of France 
ponds, undrained wet land, and swampy valleys, but merely the 
actual surface occupied by regular water-logged, pestilential 
marshes, 
Between Bourg and Lyons lies the old principality of Dombes, 
which, with those of Sologne and Forez, shares the unenviable 
reputation of being the most insalubrious province of France. 
This vast plain measures about fifty thousand acres, but late 
improvements have reduced the unhealthy surface by nearly 
one-half. The soil consists of a strong impervious clay, which, 
being undrained and scarcely cultivated, retains all the water 
that falls upon or flows over its surface. In many parts, strong 
and abundant springs have forced their way through the clay, 
and converted vast tracts into pestilential swamps. The want of 
drainage, and the still greater want of manure, have suggested to 
the scanty inhabitants who still brave that endemic fever which 
here reigns unchecked, the strange expedient of what is called 
the system of pond cultivation. The whole of the principality 
is intersected by causeways to retain the surface-water, and thus 
to form large ponds into which fish are introduced. After the 
space of three years the pond is drained, the fish sold, and the 
bottom ploughed and sown ; this water-fallow, of three years' 
duration, being equivalent to one application of manure. It 
is easy to imagine what a mass of noxious effluvia must arise 
from this immense surface of stagnant water, in a climate at 
once hot and moist, where no water can be absorbed by the soil, 
and none is allowed to flow away, or find any other means of 
escape than the atmosphere. 
The noxious influence of the emanations from marshy land 
on vegetable life are too well known to require here more than a 
passing notice, but their injurious action on animal life is no less 
evident. In the ancient province of Bresse, for instance — which 
extends from the foot of the southernmost prolongation of the 
Jura chain down to the immediate neighbourhood of Lyons — 
there are many excellent pastures, like so many islands of sound 
soil in the midst of an ocean of boggy and water-soaked land, 
cut up with large fish-ponds, the abode as well as the gene- 
rating source of those endemic fevers that desolate the whole 
province. Even upon those excellent pastures the horses, oxen, 
and sheep that graze there soon become degenerate, and, if not 
removed, fall a certain prey to the deadly effects of malaria. 
The noxious gases which arise from these swamps seem to work 
a radical modification in the animal economy. The human 
race itself bears in its outward appearance unmistakeable tokens 
of the effects of the poison. The inhabitants are of low stature, 
their complexion is of a waxy, sallow whiteness ; their flesh is 
loose and swollen, their abdomen largely developed. The vital 
