is at first
inclined to conclude with Loiseleur-Deslongchamps, that wheat
cultivated in the same country is exposed to remarkably uniform
conditions; but manures differ, seed is taken from one soil to another,
and what is far more important the plants are exposed as little as
possible to struggle with other plants, and are thus enabled to exist
under diversified conditions. In a state of nature each plant is
confined to that particular station and kind of nutriment which it can
seize from the other plants by which it is surrounded.

Wheat quickly assumes new habits of life. The summer and winter kinds
were classed by Linnaeus as distinct species; but M. Monnier[552] has
proved that the difference between them is only temporary. He sowed
winter-wheat in spring, and out of one hundred plants four alone
produced ripe seeds; these were sown and resown, and in three years
plants were reared which ripened all their seed. Conversely, nearly all
the plants raised from summer-wheat, which was sown in autumn, perished
from frost; but a few were saved and produced seed, and in three years
this summer-variety was converted into a winter-variety. Hence it is
not surprising that wheat soon becomes to a certain extent
acclimatised, and that seed brought from distant countries and sown in
Europe vegetates at first, or even for a considerable period,[553]
differently from our European varieties. In Canada the first settlers,
according to Kalm,[554] found their winters too severe for winter-wheat
brought from France, and their summers often too short for
summer-wheat; and until they procured summer-wheat from the northern
parts of Europe, which succeeded well, they thought that their {316}
country was useless for corn crops. It is notorious that the proportion
of gluten differs much under different climates. The weight of the
grain is also quickly affected by climate: Loiseleur-Deslongchamps[555]
sowed near Paris 54 varieties, obtained from the South of France and
from the Black Sea, and 52 of these yielded seed from 10 to 40 per
cent. heavier than the parent-seed. He then sent these heavier grains
back to the South of France, but there they immediately yielded lighter
seed.

All those who have closely attended to the subject insist on the close
adaptation of numerous varieties of wheat to various so