too great to make it profitable.

All this is equivalent to saying that there are certain unstable
varieties that are so influenced by climate that it is not good practice
to try and keep them up to any given standard except when they are grown
in regions which naturally develop the type that we are seeking to
maintain.

The more striking examples coming under this class are cauliflower,
millet, onions, tobacco and some of the flowering plants.

A few years ago it was supposed that the running out of varieties of
celery was due to a similar cause, that is, to unfavorable environment.
To this was ascribed the pithy quality that characterized some of the
varieties. Upon further investigations, however, it was found that this
pithy condition came about through carelessness in seed selection. There
is a more or less inherent tendency in all celery to become pithy, and
unless these plants are carefully excluded, the varieties will run out
from that cause.

The different varieties of tomatoes, egg plant and the cucurbits do not
seem to be especially affected by soil and climate, and in such
instances the varieties can be kept up only by rigid selection, no
matter how favorable that environment is under which they are grown.
With these plants there is always the inherent tendency to go back more
or less to the wild state, and lapse of care in seed selection for a
period of only a few years will result in a variety very different from
the one which we had in the beginning.

It will be seen from this that in some instances the best plan is for
each farmer or gardener to develop his own strains of crops that he
grows, while in other cases it is best to leave the selection to those
that are working in a more favored environment so far as those varieties
are concerned.

There still remains to be considered the plants that are propagated
asexually, like potatoes and all our cultivated fruits. From the fact
that a number of our standard varieties of apples and some other fruits
date back one hundred years or more, and are still as productive as at
the beginning, it is evident that some asexually propagated varieties
may be considered almost fixed or permanent.

[Illustration: Niobe willow (Salix vitellina, var. pendula nova), on
campus N.D. Agri. College, Fargo.]

The buds or scions from which new trees are started are taken
indiscriminately from the bearing trees, and since there is no great
variation in them the varieties