134 Prof. Schouw on the Geographic Dutribuion of Grasses. 
1-1 5th to 1-1 6th; 1100 to 1600 toises, 1-1 1th ; above 1600 toises, 
l-14th. 
A detailed representation of the distribution of the cultivated 
gramina would certainly be very interesting. Here we must re- 
strict ourselves to a short and general outline. We shall endea- 
vour to specify those gramina which are the prevailing ones in the 
large Zones and Continents, mentioning, in passing, those plants 
of other families which either supply the place of, or are asso- 
ciated with, the different kinds of grain, as the chief article of 
food. This distribution is determined, not merely by climate, 
but depends on the civilization, industry, and traffic, of the 
people, and often on historical events. 
Within the northern polar circle, agriculture is found only in 
a few places. In Siberia grain reaches at the utmost only to 60°, 
in the* eastern part scarcely above 55°, and in Kamtschatka there 
is no agriculture even in the most southern parts (51°). The 
polar limit of agriculture, on the north-west coast of Amerk*a, ap- 
pears to be somewhat higher ; for, in the more southerp Russian 
possessions (57° to 58°) barley and rye come to. maturity. On the 
east coast of America, it is scarcely above 50° to 52°. Only in 
Europe, namely, in Lapland, does the polar limit reach an 
unusually high latitude (70°). Beyond this, dried fish, and 
here and there potatoes, supply the place of grain. 
The grains which extend farthest to the north in Europe are 
barley and oats. These, which in the milder climates are not 
used for. bread, afford to the inhabitants of the northern parts 
of Norway and Sweden, of a part of Siberia and Scotland, their 
.chief vegetable nourishment. 
Rye is the next which become associated with these. This is 
the prevailing grain in a great part of the northern temperate 
zone, namely, in the south of Sweden and Norway, Denmark, 
and in all the lands bordering on the Baltic ; the north of 
Germany, and part of Siberia. In the latter, another very nu- 
tritious grain, buckwheat, is very frequently cultivated. In 
the zone where rye prevails, wheat is also generally to be found ; 
barley being here chiefly cultivated for the manufacture of beer ; 
and oats supply food for the horses, 
To these there follows a zone in Europe, and Western Asia, 
, where rye disappears, and wheat almost exclusively furnishes 
