At the beginning of this lecture I stated that [399] no selection is
adequate to produce either a pure strain of brightly crowned
flower-heads without atavism, or to conduce to an absolute and permanent
loss of the anomaly. During a series of years I have tested my plants in
both directions, but without the least effect. Limits are soon reached
on both sides, and to transgress these seems quite impossible.
Taking these limits as the marks of the variety, and considering all
fluctuations between them as responses to external influences working
during the life of the individual or governing the ripening of the
seeds, we get a clear picture of a permanent ever-sporting type. The
limits are absolutely permanent during the whole existence of this
already old variety. They never change. But they include so wide a range
of variability, that the extremes may be said to sport into one another,
so much the more so as one of the extremes is to be considered
morphologically as the type of the variation, while the other extreme
can hardly be distinguished from the normal form of the species.
[400]
LECTURE XIV
MONSTROSITIES
I have previously dealt with the question of the hereditary tendencies
that cause monstrosities. These tendencies are not always identical for
the same anomaly.
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