The various precautions taken to
prevent either lot being unduly favoured, have been described in the
introductory chapter. Bearing all these circumstances in mind, it may be
admitted that we have a fair basis for judging of the comparative
effects of cross-fertilisation and of self-fertilisation on the growth
of the offspring.
It will be the most convenient plan first to consider the results given
in Table 7/C, as an opportunity will thus be afforded of incidentally
discussing some important points. If the reader will look down the right
hand column of this table, he will see at a glance what an extraordinary
advantage in height, weight, and fertility the plants derived from a
cross with a fresh stock or with another sub-variety have over the
self-fertilised plants, as well as over the intercrossed plants of the
same old stock. There are only two exceptions to this rule, and these
are hardly real ones. In the case of Eschscholtzia, the advantage is
confined to fertility. In that of Petunia, though the plants derived
from a cross with a fresh stock had an immense superiority in height,
weight, and fertility over the self-fertilised plants, they were
conquered by the intercrossed plants of the same old stock in height and
weight, but not in fertility. It has, however, been shown that the
superiority of these intercrossed plants in height and weight was in all
probability not real; for if the two sets had been allowed to grow for
another month, it is almost certain that those from a cross with the
fresh stock would have been victorious in every way over the
intercrossed plants.
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