82 
SMALL QUADRUPEDS AND INSECTS. 
for the various purposes to which wood is applicable in his 
rude industry; and, when the flow of the water is thus 
checked, nature goes on with the processes I have already 
described. In such half-civilized regions, too, windfalls are 
more frequent than in those where the forest is unbroken, 
because, when openings have been made in it, for agricultural 
or other purposes, the entrance thus afforded to the wind 
occasions the sudden overthrow of hundreds of trees which 
might otherwise have stood for generations, and thus have 
fallen to the ground, only one by one, as natural decay 
brought them down.* Besides this, the flocks bred by man in 
the pastoral state, keep down the incipient growth of trees on 
the half-dried bogs, and prevent them from recovering their 
primitive condition. 
Young trees in the native forest are sometimes girdled and 
killed by the smaller rodent quadrupeds, and their growth is 
checked by birds which feed on the terminal bud; but these 
animals, as we shall see, are generally found on the skirts of 
the wood only, not in its deeper recesses, and hence the mis¬ 
chief they do is not extensive. The insects which damage 
primitive forests by feeding upon products of trees essential to 
their growth, are not numerous, nor is their appearance, in 
destructive numbers, frequent; and those which perforate the 
stems and branches, to deposit and hatch their eggs, more 
commonly select dead trees for that purpose, though, unhap¬ 
pily, there are important exceptions to this latter remark.f I 
* Careful examination of the peat mosses in North Sjaelland—which 
are so abundant in fossil wood that, within thirty years, they have yielded 
above a million of trees—shows that the trees have generally fallen from 
age and not from wind. They are found in depressions, on the declivities 
of which they grew, and they lie with the top lowest, always falling 
toward the bottom of the valley.— Vaupell, Bogens Indvandring i de 
BansTce Shove , pp. 10,14. 
t The locust insect, Clitus pictus , which deposits its eggs in the Ameri¬ 
can locust, Robinia pseudacacia , is one of these, and its ravages have been 
and still are most destructive to that very valuable tree, so remarkable for 
combining rapidity of growth with strength and durability of wood. This 
insect, I believe, has not yet appeared in Europe, where, since the so gen- 
