The table includes, as we have seen, plants belonging
to fifty-four species, but as some of these were measured during several
successive generations, there are eighty-three cases in which crossed
and self-fertilised plants were compared. As in each generation the
number of plants which were measured (given in the table) was never very
large and sometimes small, whenever in the right hand column the mean
height of the crossed and self-fertilised plants is the same within five
per cent, their heights may be considered as practically equal. Of such
cases, that is, of self-fertilised plants of which the mean height is
expressed by figures between 95 and 105, there are eighteen, either in
some one or all the generations. There are eight cases in which the
self-fertilised plants exceed the crossed by above five per cent, as
shown by the figures in the right hand column being above 105. Lastly,
there are fifty-seven cases in which the crossed plants exceed the
self-fertilised in a ratio of at least 100 to 95, and generally in a
much higher degree.
If the relative heights of the crossed and self-fertilised plants had
been due to mere chance, there would have been about as many cases of
self-fertilised plants exceeding the crossed in height by above five per
cent as of the crossed thus exceeding the self-fertilised; but we see
that of the latter there are fifty-seven cases, and of the former only
eight cases; so that the cases in which the crossed plants exceed in
height the self-fertilised in the above proportion are more than seven
times as numerous as those in which the self-fertilised exceed the
crossed in the same proportion.
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