And this rule is so
simple that exact knowledge of one instance may be considered as
sufficient to enable us to calculate from analogy what is to be expected
from a given treatment of any other anomaly. Our appreciation of
observed facts and the conditions to be chosen for intended cultures are
largely dependent on such calculations. What I am now going to describe
[393] is to be considered therefore as an experimental basis for such
expectations.
First of all comes the question how many individuals are to be grown in
a given place. When sowing plants for experimental purposes it is always
best to sow in rows, and to give as few seeds to each row as possible,
so as to insure all necessary space to the young plants. On the other
hand the seeds do not all germinate, and after sowing too thinly, gaps
may appear in the rows. This would cause not only a loss of space, but
an inequality between the plants in later life, as those nearest the
gaps would have more space and more light, and a larger area for their
roots than those growing in the unbroken rows. Hence the necessity of
using large quantities of seed and of weeding out a majority of young
plants on the spots where the greatest numbers germinate.
Crowded cultures as a rule, will give weak plants with thin stems,
mostly unbranched and bearing only small capsules.
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