EARTH-WORMS IN HISTORY. 
ARTH-WORMS are found throughout the world. 
Though few in gencra, and not many in spccies, yet 
they make up in individual numbers, for it has been estt- 
mated that they average about one hundred thousand to the 
acre. Our American species have never been monographed, 
which renders it impossible to judge of their probable num- 
ber. Their castings may be seen on commons, so as to 
cover almost entirely their surface, where the soil is poor 
and the grass short and thin, and they are almost as numer- 
ous in some of our parks where the grass grows well and 
the soil appears rich. Even on the same piece of ground 
worms are much more frequent in some places than in others, 
although no visible difference in the nature of the soil is 
manifest. They abound in paved court-yards contiguous to 
houses, and on the sidewalks in country towns, and instances 
have been reported where they have burrowed through the 
floors of very damp cellars. 
Beneath large trees few castings can be found during cer- 
tain parts of the year, and this is apparently due to the 
moisture having been sucked out of the ground by the in- 
numerable roots of the trees, an explanation which seems to 
be confirmed by the fact that such places may be observed 
covered with castings after the heavy autumnal rains. 
Although most coppices and woods support large numbers 
of worms, yet in forests of certain kinds of tree-growths, 
where the ground beneath is destitute of vegetation, not a 
casting is seen over wide reaches of ground, even during the 
autumn. In mountainous districts worms are mostly rare, it 
