of Saxony,
and speaks German like the downstream folk; but its upper course, hemmed
in by the Erz and Riesen Mountains, shows the short, dark and
broad-headed people of the Bohemian basin, speaking the Czech
language.[693] On the Danube, too, the same thing is true. The upper
stream is German in language and predominantly Alpine in race stock down
to the Austro-Hungarian boundary; from this point to the Drave mouth it
is Hungarian; and from the Drave to the Iron Gate it is Serbo-Croatian
on both banks.[694] Lines of ethnic demarcation, therefore, cut the Elbe
and Danube transversely, not longitudinally. [See map page 223.]

The statements of Caesar and Pliny that the Seine and Marne formed the
boundary between the Gauls and Belgians, and the Garonne that between
the Gauls and Aquitanians, must be accepted merely as general and
preliminary; for exceptions are noted later in the text. Parisii, for
instance, were represented as holding both banks of the Seine and Marne
at their confluence, and the Gallic Bituriges were found on the
Aquitanian side of the Garonne estuary.

[Sidenote: Scientific river boundaries.]

Only under peculiar conditions do rivers become effective as ethnic,
tribal or political boundaries. Most often it is some physiographic
feature which makes the stream an obstacle to communication, and lends
it the character of a scientific boundary. The division of the Alpine
foreland of southern Germany first into tribal and later into political
provinces by the Iller, Lech, Inn, and Salzach can be ascribed in part
to the tumultuous course of these streams from the mountains to the
Danube, which renders them useless for communication.[695] The lower
Danube forms a well maintained linguistic boundary between the
Bulgarians and Roumanians, except in the northwest corner of Bulgaria,
where the hill country between the Timok River and the Danube has
enticed a small group of Roumanians across to the southern side. From
this point down the stream, a long stretch of low marshy bank on the
northern side, offering village sites only at the few places where the
loess terrace of Roumania comes close to the river, exposed to
overflows, strewn with swamps and lakes, and generally unfit for
settlement, has made the Danube an effective barrier.[696] Similarly, the
broad, sluggish Shannon River, which spreads out to lake breadth at
close intervals in its course across the boggy central plain of Ireland,
has from the earlies