e the
logs move in the direction which they wished to go. Perhaps this
explanation is as good as any, inasmuch as the beginnings of modern
transportation still dwell in the mist of the past. However, in
support of the log theory is the fact that modern races use primitive
boats made of long reeds tied together, forming a loglike structure.
The _balsa_ of the Indians of the north coasts of South America is a
very good representation of this kind of boat.

Evidently, the first canoes were made by hollowing logs and sharpening
the ends at bow and stern. This form of boat-making has been carried
to a high degree of skill by the {104} Indians of the northwest coast
of America and by the natives of the Hawaiian Islands. The birch-bark
canoe, made for lighter work and overland transportation, is more
suggestive of the light reed boat than of the log canoe. Also, the
boats made of a framework covered with the skins of animals were
prominent at certain periods of the development of races who lived on
animal food. But later the development of boats with frames covered
with strips of board and coated with pitch became the great vehicle of
commerce through hundreds of years. It certainly is a long journey
from the floating log to the modern floating passenger palace, freight
leviathan, or armed dreadnought, but the journey was accomplished by
thousands of steps, some short and some long, through thousands of
years of progress.

_Trade, or Exchange of Goods_.--In Mr. Clark Wissler's book on _Man and
Culture_, he has shown quite conclusively that there are certain
culture areas whereby certain inventions, discoveries, or customs have
originated and spread over a given territory. This recognition of a
centre of origin of custom or invention is in accordance with the whole
process of social development. For instance, in a given area occupied
by modern civilized people, there are a very few who invent or
originate things, and others follow through imitation or suggestion.
So it was with the discoveries and inventions of primitive man. For
example, we know that in Oklahoma and Arkansas, as well as in other
places in the United States, certain stone quarries or mines are found
that produce a certain kind of flint or chert used in making
arrow-heads or spearheads and axes. Tribes that developed these traded
with other tribes that did not have them, so that from these centres
implements were scattered all over the West. A pers