This good fortune however, I did have with the wild teasel or _Dipsacus
sylvestris_. [404] Stems of this and of allied species are often met
with and have been described by several writers, but they were always
considered as accidents and nobody had ever tried to cultivate them. In
the summer of 1885 I saw among a lot of normal wild teasels, two nicely
twisted stems in the botanical garden of Amsterdam. I at once proposed
to ascertain whether they would yield a hereditary race and had all the
normal individuals thrown away before the flowering time. My two plants
flowered in this isolated condition and were richly pollinated by
insects. Of course, at that time, I knew nothing of the dependency of
monstrosities on external conditions, and made the mistake of sowing the
seeds and cultivating the next generation in too great numbers on a
small space. But nevertheless the anomaly was repeated, and the aberrant
individuals were once more isolated before flowering. The third
generation repeated the second, but produced sixty twisted stems on some
1,600 individuals. The result was very striking and quite sufficient for
all further researches, but the normal condition of the race was not
reached. This was the case only after I had discovered the bad effects
of growing too many plants in a limited space. In the fourth generation
I restricted my whole culture to about 100 individuals, and by this
simple [405] means at once got up to 34% of twisted stems. This
proportion has since remained practically the same. I have selected and
isolated my plants during five succeeding generations, but without any
further result, the percentage of twisted stems fluctuating between 30
and about 45 according to the size of the cultures and the favorableness
or unfavorableness of the weather.
It is very interesting to note that all depends on the question whether
one has the good fortune of finding a rich race or not, as this
pedigree-culture shows. Afterwards everything depends on treatment and
very little on selection. As soon as the treatment becomes adequate, the
full strength of the race at once displays itself, but afterwards no
selection is able to improve it to any appreciable amount. Of course, in
the long run, the responses will be the same as those of the pistilloid
poppies on the average, and some influence of selection will show itself
on closer scrutiny.
Compared with the polycephalous poppies my race of twisted teasels is
much richer in atavists. They are never absent, and always constitute a
large part of each generation and each bed, comprising somewhat more
than half of the individuals. Intermediate stages between them and the
wholly twisted stems are not wanting, [406] and a whole series of steps
may easily be observed from sufficiently large cultures. But they are
always relatively rare, and any lot of plants conveys the idea of a
dimorphous race, the small twisted stems contrasting strongly with the
tall straight ones.
Public-domain text, read in full here on John Shaqi.
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