bundant yield of both. As such instances show how
these pests have been regarded by the agricultural world, one would
think that it was now time for us to hear of their diminishing in
number. But no such diminution can be asserted.

The history of the migration of seeds is full of the most curious
statistics. The reviewer of a recent publication makes the following
interesting statement.

"The lonely island of St. Helena, for example, at the time of its
discovery in 1501, produced about sixty vegetable species. Its flora now
comprises seven hundred and fifty species. The faculty of spontaneous
reproduction supposes a greater power of accommodation than we find in
most domesticated plants. Although every wild species affects a habitat
of a particular character, it will grow under conditions extremely
unlike those of its birthplace. The seven hundred new species which have
found their way to St. Helena within three centuries and a half were
probably not in very large proportion designedly introduced there by
human art. As a general rule, it may be assumed that man has
intentionally transferred fewer plants than he has accidentally into
countries foreign to them. Tares follow the wheat. The weeds that grow
among the cereal grains, and form the pest of the kitchen-garden, are
the same in America as in Europe. Some years ago, the author made a
collection of weeds in the wheat-fields of Upper Egypt, and another in
the gardens on the Bosphorus. Nearly all the plants were identical with
those that grow under the same conditions in New England. The change
from one locality to another is effected by a thousand casual
circumstances. The upsetting of the wagon of an emigrant in his journey
across the Western plains may scatter upon the ground the seeds he
designed for his garden. The herbs which fill so important a place in
the rustic _materia medica_ of the Eastern States spring up along the
prairie-paths just opened by the caravan of the settler. The _hortus
siccus_ of a botanist may accidentally sow seeds from the foot of the
Himalayas on the plains that skirt the Alps. It is a fact frequently
observed, that exotics transplanted to foreign climates suited to their
growth escape from the flower-garden, and naturalize themselves among
the spontaneous vegetation of the pastures. The straw and grass employed
in packing the sculptures of Thorwaldsen were scattered in the
court-yard of the museum in Copenhagen, where they are deposit