180 
ARE SOILS ENRICHED, IMPOVERISHED, [Part III 
I think that there is an aerial denudation, as 
well as an aqueous denudation, and an aerial 
deposit, as well as an aqueous deposit; and 
that woods are not only free from the aerial 
denudation, but are favoured receptacles for the 
aerial deposit: and that these circumstances 
more than compensate woods even for the crops 
taken from them by man. Carnivorous animals 
prey on the herbivorous, but the longest-lived 
animals and plants die, and their hardest parts 
decay; so that, on the average, the entire mass 
of a year’s growth of all terrestrial vegetation 
may be considered as taken annually from below 
the surface, and annually deposited afresh above 
the surface. Much of the organic or combus¬ 
tible part of this growth goes into the atmosphere 
in the form of gases, to be returned again to the 
earth in rain. Of the inorganic or incombus¬ 
tible part, or what would be the ashes of animals 
and plants if burnt, much is washed into the 
earth by rain, much ploughed in as manure, 
much washed into the sea with other soil. But, 
doubtless, much of this extremely “ finely 
divided matter ” is transported by wind : and 
although, in bulk, this aerial deposit is a joke 
to aqueous deposit, its fertilising qualities are 
great ; and as woods catch a great quantity of 
