UTILITY OF EARTHWORMS. 
101 
who has shown that in a few years they have actually elevated 
the surface of fields by a large layer of rich mould, several inches 
thick—thus affording nourishment to the roots of grasses, and 
increasing the productiveness of the soil.” 
It should be added that the writer quoted, and others who 
have discussed the subject, have overlooked one very import¬ 
ant element in the fertilization produced by earthworms. I 
refer to the enrichment of the soil by their excreta during life, 
and by the decomposition of their remains when they die. 
The manure thus furnished is as valuable as the like amount 
of similar animal products derived from higher organisms, and 
when we consider the prodigious numbers of these worms 
found on a .single square yard of some soils, we may easily see 
that they furnish no insignificant contribution to the nutritive 
material required for the growth of plants.* 
The perforations of the earthworm mechanically affect the 
texture of the soil and its permeability by water, and they 
therefore have a certain influence on the form and character 
of surface. But the geographical importance of insects proper, 
as well as of worms, depends principally on their connection 
* I believe there is no foundation for the supposition that earthworms 
attack the tuber of the potato. Some of them, especially one or two spe¬ 
cies employed by anglers as bait, if natives of the woods, are at least rare 
in shaded grounds, but multiply very rapidly after the soil is brought 
under cultivation. Forty or fifty years ago they were so scarce in the 
newer parts of New England, that the rustic fishermen of every village 
kept secret the few places where they were to be found in their neighbor¬ 
hood, as a professional mystery, but at present one can hardly turn over a 
shovelful of rich moist soil anywhere, without unearthing several of them. 
A very intelligent lady, born in the woods of Northern New England, told 
me that, in her childhood, these worms were almost unknown in that 
region, though anxiously sought for by the anglers, but that they increased 
as the country was cleared, and at last became so numerous in some places, 
that the water of springs, and even of shallow wells, which had formerly 
been excellent, was rendered undrinkable by the quantity of dead worms 
that fell into them. The increase of the robin and other small birds which 
follow the settler when he has prepared a suitable home for them, at last 
checked the excessive multiplication of the worms, and abated the nui¬ 
sance. 
