INFLUENCE OF THE FOREST ON FLOODS. 233 
eral earth below, and thus is ready to receive a new supply; 
and, besides, the bed of leaves not yet converted to mould takes 
up and retains a very considerable proportion of snow-water, as 
well as of rain. 
The stems of trees, too, and of underwood, the trunks and 
stumps and roots of fallen timber, the mosses and fungi and the 
numerous inequalities of the ground observed in all forests, 
oppose a mechanical resistance to the flow of water over the 
surface, which sensibly retards the rapidity of its descent down 
declivities, and diverts and divides streams which may have 
already accumulated from smaller threads of water.* 
* Tn a letter addressed to the Minister of Public Works, after the terrible 
inundations of 1857, the late Emperor of France thus happily expressed him- 
self: ‘‘Before we seek the remedy for an evil, we inquire into its catse. 
Whence come the sudden floods of our rivers? From the water which falls 
on the mountains, not from that which falls on the plains. The waters which 
fall on our fields produce but few rivulets, but those which fall on our roofs 
and are collected in the gutters, form small streams at once. Now, the roofs 
are mountains—the gutters are valleys.” 
‘¢To continue the comparison,” observes D’Héricourt, ‘‘ roofs are smooth 
and impermeable, and the rain-water pours rapidly off from their surfaces ; 
but this rapidity of flow would be greatly diminished if the roofs were carpeted 
with mosses and grasses; more still, if they were covered with dry leaves, 
little shrubs, strewn branches, and other impediments—in short, if they were 
wooded.”—Annales Forestiéres, Dec, 1857, p. 311. 
The mosses and fungi play a more important part in regulating the humid- 
ity of the air and of the soil than writers on the forest have usually assigned 
to them. They perish with the trees they grow on; but, in many situations, 
nature provides a compensation for the tree-mosses and fungi in ground 
species, which, on cold soils, especially those with a northern exposure, spring 
up abundantly both before the woods are felled, and when the land is cleared 
and employed for pasturage, or deserted. These humble plants discharge a 
portion of the functions appropriated to the wood, and while they render the 
soil of improved lands much less fit for agricultural use, they, at the same time, 
prepare it for the growth of a new harvest of trees, when the infertility they 
produce shall have driven man to abandon it and suffer it to relapse into the 
hands of nature. 
In primitive forests, when the ground is not too moist to admit of a dense 
erowth of trees, the soil is generally so thickly covered with leaves that there 
is little room for ground mosses and mushrooms. In the more open artificial 
woods of Hurope these forms of vegetation, as well as many more attractive 
