)
We can thus understand the striking parallelism, which has been shown to exist
between the effects of illegitimately uniting heterostyled plants and of
crossing distinct species. The great difference in the degree of sterility
between the various heterostyled species when illegitimately fertilised, and
between the two forms of the same species when similarly fertilised, harmonises
well with the view that the result is an incidental one which follows from
changes gradually effected in their reproductive systems, in order that the
sexual elements of the distinct forms should act perfectly on one another.
TRANSMISSION OF THE TWO FORMS BY HETEROSTYLED PLANTS.
The transmission of the two forms by heterostyled plants, with respect to which
many facts were given in the last chapter, may perhaps be found hereafter to
throw some light on their manner of development. Hildebrand observed that
seedlings from the long-styled form of Primula Sinensis when fertilised with
pollen from the same form were mostly long-styled, and many analogous cases have
since been observed by me. All the known cases are given in Tables 6.36 and
6.37.
TABLE 6.36. Nature of the offspring from illegitimately fertilised dimorphic
plants.
Column 1: Species and form.
Column 2: Number of long-styled offspring.
Column 3: Number of short-styled offspring.
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