37 high; so that
there was not much difference between the three sets, the
self-fertilised plants having a slight advantage. Nor was there any
great difference when only the plants under 36 inches in height were
excluded. Nor again when all the plants, however much dwarfed and
unhealthy, were included. In this latter case the Colchester-crossed
gave the lowest average of all; and if these plants had been in any
marked manner superior to the other two lots, as from my former
experience I fully expected they would have been, I cannot but think
that some vestige of such superiority would have been evident,
notwithstanding the very unhealthy condition of most of the plants. No
advantage, as far as we can judge, was derived from intercrossing two of
the grandchildren of Hero, any more than when two of the children were
crossed. It appears therefore that Hero and its descendants have varied
from the common type, not only in acquiring great power of growth, and
increased fertility when subjected to self-fertilisation, but in not
profiting from a cross with a distinct stock; and this latter fact, if
trustworthy, is a unique case, as far as I have observed in all my
experiments.]
SUMMARY ON THE GROWTH, VIGOUR, AND FERTILITY OF THE SUCCESSIVE
GENERATIONS OF THE CROSSED AND SELF-FERTILISED PLANTS OF Ipomoea
purpurea, TOGETHER WITH SOME MISCELLANEOUS OBSERVATIONS.
In Table 2/17, we see the average or mean heights of the ten successive
generations of the intercrossed and self-fertilised plants, grown in
competition with each other; and in the right hand column we have the
ratios of the one to the other, the height of the intercrossed plants
being taken at 100.
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