These trials were made, not for the sake of comparing the growth of the crossed and self-fertilised seedlings, but because I had seen it stated that these varieties would not naturally intercross when growing uncovered and near one another.  This statement proved quite erroneous; but the white-green variety was in some degree sterile in my garden, producing little pollen and few seeds.  It was therefore no wonder that seedlings raised from the self-fertilised flowers of this variety were greatly exceeded in height by seedlings from a cross between it and the more vigorous crimson-green variety; and nothing more need be said about this experiment.

The seedlings from the reciprocal cross, that is, from the crimson-green variety fertilised with pollen from the white-green variety, offer a somewhat more curious case.  A few of these crossed seedlings reverted to a pure green variety with their leaves less cut and curled, so that they were altogether in a much more natural state, and these plants grew more vigorously and taller than any of the others.  Now it is a strange fact that a much larger number of the self-fertilised seedlings from the crimson-green variety than of the crossed seedlings thus reverted; and as a consequence the self-fertilised seedlings grew taller by 2 1/2 inches on an average than the crossed seedlings, with which they were put into competition.  At first, however, the crossed seedlings exceeded the self-fertilised by an average of a quarter of an inch.  We thus see that reversion to a more natural condition acted more powerfully in favouring the ultimate growth of these plants than did a cross; but it should be remembered that the cross was with a semi-sterile variety having a feeble constitution.

Iberis umbellata.

Var.  KERMESIANA.

This variety produced plenty of spontaneously self-fertilised seed under a net.  Other plants in pots in the greenhouse were left uncovered, and as I saw small flies visiting the flowers, it seemed probable that they would be intercrossed.  Consequently seeds supposed to have been thus crossed and spontaneously self-fertilised seeds were sown on opposite sides of a pot.  The self-fertilised seedlings grew from the first quicker than the supposed crossed seedlings, and when both lots were in full flower the former were from 5 to 6 inches higher than the crossed!  I record in my notes that the self-fertilised seeds from which these self-fertilised plants were raised were not so well ripened as the crossed; and this may possibly have caused the great difference in their growth, in a somewhat analogous manner as occurred with the self-fertilised plants of the eighth generation of Ipomoea raised from unhealthy parents.  It is a curious circumstance, that two other lots of the above seeds were sown in pure sand mixed with burnt earth, and therefore without any organic matter; and here the supposed crossed seedlings grew to double the height of the self-fertilised, before both lots died, as necessarily occurred at an early period.  We shall hereafter meet with another case apparently analogous to this of Iberis in the third generation of Petunia.