Most of these cases shown not to be real exceptions to the rule that
cross-fertilisation is beneficial.
Summary of results.
Relative weights of the crossed and self-fertilised plants.
The details which have been given under the head of each species are so
numerous and so intricate, that it is necessary to tabulate the results.
In Table 7/A, the number of plants of each kind which were raised from a
cross between two individuals of the same stock and from self-fertilised
seeds, together with their mean or average heights, are given. In the
right hand column, the mean height of the crossed to that of the
self-fertilised plants, the former being taken as 100, is shown. To make
this clear, it may be advisable to give an example. In the first
generation of Ipomoea, six plants derived from a cross between two
plants were measured, and their mean height is 86.00 inches; six plants
derived from flowers on the same parent-plant fertilised with their own
pollen were measured, and their mean height is 65.66 inches. From this
it follows, as shown in the right hand column, that if the mean height
of the crossed plants be taken as 100, that of the self-fertilised
plants is 76. The same plan is followed with all the other species.
The crossed and self-fertilised plants were generally grown in pots in
competition with one another, and always under as closely similar
conditions as could be attained.
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