strongly prepotent over the other; and instances are known of a variety crossed
by another, producing offspring which in certain characters, as in colour,
hairiness, etc., have proved identical with the pollen-bearing parent, and quite
dissimilar to the mother-plant (2/11. I have given instances in my work 'On the
Variation of Animals and Plants under Domestication' chapter 15 2nd edition
volume 2 page 69.); but I do not know of any instance of the offspring of a
cross perfectly resembling, in a considerable number of important characters,
the father alone. It is, therefore, very improbable that a pure cowslip crossed
by a primrose should ever produce a primrose in appearance pure. Although the
facts given by Dr. Herbert and Professor Henslow are difficult to explain, yet
until it can be shown that a cowslip or a primrose, carefully protected from
insects, will give birth to at least oxlips, the cases hitherto recorded have
little weight in leading us to admit that the cowslip and primrose are varieties
of one and the same species.

Negative evidence is of little value; but the following facts may be worth
giving:--Some cowslips which had been transplanted from the fields into a
shrubbery were again transplanted into highly manured land. In the following
year they were protected from insects, artificially fertilised, and the seed
thus procured was sown in a hotbed. The young plants were afterwards planted
out, some in very rich soil, some in stiff poor clay, some in old peat, and some
in pots in the greenhouse; so that these plants, 765 in number, as well as their
parents, were subjected to diversified and unnatural treatment; but not one of
them presented the least variation except in size--those in the peat attaining
almost gigantic dimensions, and those in the clay being much dwarfed.

I do not, of course, doubt that cowslips exposed during SEVERAL successive
generations to changed conditions would vary, and that this might occasionally
occur in a state of nature. Moreover, from the law of analogical variation, the
varieties of any one species of Primula would probably in some cases resemble