altogether, attributed to their lessened size or height; this being
chiefly due to their lessened constitutional vigour, so that they were
not able to compete with the crossed plants growing in the same pots.
The seeds produced by the crossed flowers on the crossed plants were not
always heavier than the self-fertilised seeds on the self-fertilised
plants. The lighter seeds, whether produced from crossed or
self-fertilised flowers, generally germinated before the heavier seeds.
I may add that the crossed plants, with very few exceptions, flowered
before their self-fertilised opponents, as might have been expected from
their greater height and vigour.

The impaired fertility of the self-fertilised plants was shown in
another way, namely, by their anthers being smaller than those in the
flowers on the crossed plants. This was first observed in the seventh
generation, but may have occurred earlier. Several anthers from flowers
on the crossed and self-fertilised plants of the eighth generation were
compared under the microscope; and those from the former were generally
longer and plainly broader than the anthers of the self-fertilised
plants. The quantity of pollen contained in one of the latter was, as
far as could be judged by the eye, about half of that contained in one
from a crossed plant. The impaired fertility of the self-fertilised
plants of the eighth generation was also shown in another manner, which
may often be observed in hybrids--namely, by the first-formed flowers
being sterile. For instance, the fifteen first flowers on a
self-fertilised plant of one of the later generations were carefully
fertilised with their own pollen, and eight of them dropped off; at the
same time fifteen flowers on a crossed plant growing in the same pot
were self-fertilised, and only one dropped off. On two other crossed
plants of the same generation, several of the earliest flowers were
observed to fertilise themselves and to produce capsules. In the plants