ges of aggregation, may we not see paralleled the
union of groups of connate tribes into nations? Though, in regions where
circumstances permit, the tribes descended from some original tribe
migrate in all directions, and become far removed and quite separate;
yet, where the territory presents barriers to distant migration, this
does not happen: the small kindred communities are held in closer
contact, and eventually become more or less united into a nation. The
contrast between the tribes of American Indians and the Scottish clans,
illustrates this. And a glance at our own early history, or the early
histories of continental nations, shows this fusion of small simple
communities taking place in various ways and to various extents. As says
M. Guizot, in his _History of the Origin of Representative
Government_,--

"By degrees, in the midst of the chaos of the rising society, small
aggregations are formed which feel the want of alliance and union
with each other.... Soon inequality of strength is displayed among
neighbouring aggregations. The strong tend to subjugate the weak,
and usurp at first the rights of taxation and military service.
Thus political authority leaves the aggregations which first
instituted it, to take a wider range."

That is to say, the small tribes, clans, or feudal groups, sprung mostly
from a common stock, and long held in contact as occupants of adjacent
lands, gradually get united in other ways than by kinship and proximity.

A further series of changes begins now to take place, to which, as
before, we find analogies in individual organisms. Returning to the
_Hydrozoa_, we observe that in the simplest of the compound forms the
connected individuals are alike in structure, and perform like
functions; with the exception that here and there a bud, instead of
developing into a stomach, mouth, and tentacles, becomes an egg-sac. But
with the oceanic _Hydrozoa_ this is by no means the case. In the
_Calycophoridae_ some of the polypes growing from the common germ, become
developed and modified into large, long, sack-like bodies, which, by
their rhythmical contractions, move through the water, dragging the
community of polypes after them. In the _Physophoridae_ a variety of
organs similarly arise by transformation of the budding polypes; so that
in creatures like the _Physalia_, commonly known as the "Portuguese
Man-of-war," instead of that tree-like group of similar