In this and the four following cases, the details may be found
under the head of each species. In eight pots, in which the plants did
not grow much crowded, the flower-stems on sixteen intercrossed plants
were in height to those on sixteen self-fertilised plants, as 100 to 94.
In the two other pots on which the plants grew much crowded, the
flower-stems on nine intercrossed plants were in height to those on nine
self-fertilised plants, as 100 to 90. That the intercrossed plants in
these two latter pots had a real advantage over their self-fertilised
opponents, was well shown by their relative weights when cut down, which
was as 100 to 78. The mean height of the flower-stems on the twenty-five
intercrossed plants in the ten pots taken together, was to that of the
flower-stems on the twenty-five self-fertilised plants, as 100 to 92.
Thus the intercrossed plants were certainly superior to the
self-fertilised in some degree; but their superiority was small compared
with that of the offspring from a cross between distinct plants over the
self-fertilised, this being in the ratio of 100 to 70 in height. Nor
does this latter ratio show at all fairly the great superiority of the
plants derived from a cross between distinct individuals over the
self-fertilised, as the former produced more than twice as many
flower-stems as the latter, and were much less liable to premature
death.
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