Earth-Worms in History. 61 
is enlarged, or a fresh one is made close by, so that a larger 
number of leaves may be drawn in. Generally the interstices 
between the drawn-in leaves are filled with moist, viscid 
earth ejected from their bodies, thus rendering them doubly 
secure. Hundreds of such plugged burrows may be seen 
during the autumnal and early winter months. 
When leaves, petioles, sticks, etc., cannot be obtained for 
the mouths of their burrows, heaps of stones, smooth, 
rounded pebbles, are utilized for protection. When the 
stones are removed and the surface of the ground is cleared 
for some inches round the burrow, the worms may be seen 
with their tails fixed in their burrows dragging the stones 
inward by the aid of their mouths, stones weighing as much 
as two ounces often being found in the little heaps, which 
goes to show how strong these apparently weak creatures 
are. Work of this kind is usually performed during the night, 
although objects have been occasionally known to be drawn 
into the burrows during the day. What advantage worms 
derive from plugging up the mouths of their burrows, or from 
piling stones over them, cannot be satisfactorily answered. 
They do not act in this manner when they eject much earth 
from their burrows, for then their castings serve to cover the 
mouth. Perhaps the plugs serve to protect them from the 
attacks of scolopenders, their most inveterate enemies, or to 
enable them to remain with safety with their heads close to 
the mouths of their burrows, which they like so well to do, 
but which, unless protected, costs many a fellow its life. 
Besides, may not the plugs check the free ingress of the 
lowest stratum of air, when chilled by radiation at night, 
from the surrounding ground and herbage? The last view 
of the matter seems especially well taken, because worms 
kept in pots where there is fire, having no cold air with 
which to contend, plug up their burrows in a slovenly man- 
ner, and because they often coat the upper part of their 
burrows with leaves, apparently to prevent their bodies from 
coming into contact with the cold, damp earth. But the 
