CONFLICTING INFLUENCES. 191 
The daily discharge of a quantity of aqueous vapor correspond- 
ing to a rain-fall of one inch and a fifth into the cool air of the 
forest would produce a perpetual shower, or at least drizzle, un- 
less, indeed, we suppose a rapidity of absorption and condensa- 
tion by the ground, and of transmission through the soil to the 
roots and through them and the vessels of the tree to the leaves, 
much greater than has been shown by direct observation. Not- 
withstanding the high authority of Schleiden, therefore, it seems 
impossible to reconcile his estimates with facts commonly ob- 
served and well established by competent investigators. Ience 
the important question of the supply, demand, and expenditure 
of water by forest vegetation must remain undecided, until it 
can be determined by something approaching to satisfactory 
direct experiment.* 
Balance of Conflicting Influences of Forest on Atmospheric 
Lleat and umidity. 
We have shown that the forest, considered as dead matter, 
tends to diminish the moisture of the air, by preventing the 
sun’s rays from reaching the ground and evaporating the water 
that falls upon the surface, and also by spreading over the earth 
a spongy mantle which sucks up and retains the humidity it 
receives from the atmosphere, while, at the same time, this coy- 
ering actsin the contrary direction by accumulating, in a reser- 
voir not wholly inaccessible to vaporizing influences, the water 
of precipitation which might otherwise suddenly sink deep into 
the bowels of the earth, or flow by superficial channels to other 
climatic regions. We now see that, as a living organism, it 
though the ambient atmosphere may hold in suspension, in the form of fog, 
water enough to obscure its transparency, and to produce the sensation of 
moisture on the skin, the air, in which the finely divided water floats, may 
be charged with even less than an average proportion of humidity. 
* According to Cezanne, SURELL, Etude sur les Torrents, 2° édition, ii., p. 
100, experiments reported in the Revue des Eaux et Foréts for August, 1868, 
showed the evaporation from a living tree to be ‘‘ almost insignificant.’? De- 
tails are not given. 
