The same holds good with respect to the mid-styled and short-styled
forms. Therefore with trimorphic species six of the eighteen unions yield
legitimate offspring, and twelve yield illegitimate offspring.
I will give the results of my experiments in detail, partly because the
observations are extremely troublesome, and will not probably soon be repeated--
thus, I was compelled to count under the microscope above 20,000 seeds of
Lythrum salicaria--but chiefly because light is thus indirectly thrown on the
important subject of hybridism.
Lythrum salicaria.
Of the twelve illegitimate unions two were completely barren, so that no seeds
were obtained, and of course no seedlings could be raised. Seedlings were,
however, raised from seven of the ten remaining illegitimate unions. Such
illegitimate seedlings when in flower were generally allowed to be freely and
legitimately fertilised, through the agency of bees, by other illegitimate
plants belonging to the two other forms growing close by. This is the fairest
plan, and was usually followed; but in several cases (which will always be
stated) illegitimate plants were fertilised with pollen taken from legitimate
plants belonging to the other two forms; and this, as might have been expected,
increased their fertility. Lythrum salicaria is much affected in its fertility
by the nature of the season; and to avoid error from this source, as far as
possible, my observations were continued during several years.
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