ollowed. The
great growers of potatoes in Lancashire formerly used to get tubers
from Scotland, but they found that "a change from the moss-lands, and
_vice versa_, was generally sufficient." In former times in France the
crop of potatoes in the Vosges had become reduced in the course of
fifty or sixty years in the proportion from 120-150 to 30-40 bushels;
and the famous Oberlin attributed the surprising good which he effected
in large part to changing the sets.[326]

A well-known practical gardener, Mr. Robson[327] positively states that
he has himself witnessed decided advantage from obtaining bulbs of the
onion, tubers of the potato, and various seeds, all of the same kind,
from different soils and distant parts of England. He further states
that with {147} plants propagated by cuttings, as with the Pelargonium,
and especially the Dahlia, manifest advantage is derived from getting
plans of the same variety, which have been cultivated in another place;
or, "where the extent of the place allows, to take cuttings from one
description of soil to plant on another, so as to afford the change
that seems so necessary to the well-being of the plants." He maintains
that after a time an exchange of this nature is "forced on the grower,
whether he be prepared for it or not." Similar remarks have been made
by another excellent gardener, Mr. Fish, namely, that cuttings of the
same variety of Calceolaria, which he obtained from a neighbour,
"showed much greater vigour than some of his own that were treated in
exactly the same manner," and he attributed this solely to his own
plants having become "to a certain extent worn out or tired of their
quarters." Something of this kind apparently occurs in grafting and
budding fruit-trees; for, according to Mr. Abbey, grafts or buds
generally take on a distinct variety or even species, or on a stock
previously grafted, with greater facility than on stocks raised from
seeds of the variety which is to be grafted; and he believes this
cannot be altogether explained by the stocks in question being better
adapted to the soil and climate of the place. It should, however, be
added, that varieties grafted or budded on very distinct kinds, though
they may take more readily and grow at first more vigorously than when
grafted on closely allied stocks, afterwards often be