ered, they have to
describe a zigzag whose windings and extent are determined by the
leader's fancy. Hence come gropings and roamings which are sometimes
prolonged to the point of causing the herd to spend the night out of
doors. It is not a serious matter. They collect into a motionless
cluster. To-morrow the search will start afresh and will sooner or
later be successful. Oftener still the winding curve meets the
guide-thread at the first attempt. As soon as the first caterpillar has
the rail between his legs, all hesitation ceases; and the band makes
for the nest with hurried steps.

The use of this silk-tapestried roadway is evident from a second point
of view. To protect himself against the severity of the winter which he
has to face when working, the Pine Caterpillar weaves himself a shelter
in which he spends his bad hours, his days of enforced idleness. Alone,
with none but the meagre resources of his silk-glands, he would find
difficulty in protecting himself on the top of a branch buffeted by the
winds. A substantial dwelling, proof against snow, gales and icy fogs,
requires the cooperation of a large number. Out of the individual's
piled-up atoms, the community obtains a spacious and durable
establishment.

The enterprise takes a long time to complete. Every evening, when the
weather permits, the building has to be strengthened and enlarged. It
is indispensable, therefore, that the corporation of workers should not
be dissolved while the stormy season continues and the insects are
still in the caterpillar stage. But, without special arrangements, each
nocturnal expedition at grazing-time would be a cause of separation. At
that moment of appetite for food there is a return to individualism.
The caterpillars become more or less scattered, settling singly on the
branches around; each browses his pine-needle separately. How are they
to find one another afterwards and become a community again?

The several threads left on the road make this easy. With that guide,
every caterpillar, however far he may be, comes back to his companions
without ever missing the way. They come hurrying from a host of twigs,
from here, from there, from above, from below; and soon the scattered
legion reforms into a group. The silk thread is something more than a
road-making expedient: it is the social bond, the system that keeps the
members of the brotherhood indissolubly united.

At the head of every procession, long or short, goes