_On the number of worms which live within a given space_. We will now
show, firstly, what a vast number of worms live unseen by us beneath our
feet, and, secondly, the actual weight of the earth which they bring up
to the surface within a given space and within a given time. Hensen, who
has published so full and interesting an account of the habits of worms,
{148} calculates, from the number which he found in a measured space,
that there must exist 133,000 living worms in a hectare of land, or
53,767 in an acre. This latter number of worms would weigh 356 pounds,
taking Hensen s standard of the weight of a single worm, namely, three
grams. It should, however, be noted that this calculation is founded on
the numbers found in a garden, and Hensen believes that worms are here
twice as numerous as in corn-fields. The above result, astonishing
though it be, seems to me credible, judging from the number of worms
which I have sometimes seen, and from the number daily destroyed by birds
without the species being exterminated. Some barrels of bad ale were
left on Mr. Miller s land, {149} in the hope of making vinegar, but the
vinegar proved bad, and the barrels were upset. It should be premised
that acetic acid is so deadly a poison to worms that Perrier found that a
glass rod dipped into this acid and then into a considerable body of
water in which worms were immersed, invariably killed them quickly. On
the morning after the barrels had been upset, the heaps of worms which
lay dead on the ground were so amazing, that if Mr. Miller had not seen
them, he could not have thought it possible for such numbers to have
existed in the space. As further evidence of the large number of worms
which live in the ground, Hensen states that he found in a garden
sixty-four open burrows in a space of 141 2 square feet, that is, nine in 2
square feet. But the burrows are sometimes much more numerous, for when
digging in a grass-field near Maer Hall, I found a cake of dry earth, as
large as my two open hands, which was penetrated by seven burrows, as
large as goose-quills.
_Weight of the earth ejected from a single burrow_, _and from all the
burrows within a given space_. With respect to the weight of the earth
daily ejected by worms, Hensen found that it amounted, in the case of
some worms which he kept in confinement, and which he appears to have fed
with leaves, to only 0.5 gram, or less than 8 grains per diem. But a
very much larger amount must be ejected by worms in their natural state,
at the periods when they consume earth as food instead of leaves, and
when they are making deep burrows. This is rendered almost certain by
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