CONVOLVULACEAE.

Ipomoea purpurea, comparison of the height and fertility of the crossed
and self-fertilised plants during ten successive generations.
Greater constitutional vigour of the crossed plants.
The effects on the offspring of crossing different flowers on the same
plant, instead of crossing distinct individuals.
The effects of a cross with a fresh stock.
The descendants of the self-fertilised plant named Hero.
Summary on the growth, vigour, and fertility of the successive crossed
and self-fertilised generations.
Small amount of pollen in the anthers of the self-fertilised plants of
the later generations, and the sterility of their first-produced
flowers.
Uniform colour of the flowers produced by the self-fertilised plants.
The advantage from a cross between two distinct plants depends on their
differing in constitution.

A plant of Ipomoea purpurea, or as it is often called in England the
convolvulus major, a native of South America, grew in my greenhouse. Ten
flowers on this plant were fertilised with pollen from the same flower;
and ten other flowers on the same plant were crossed with pollen from a
distinct plant. The fertilisation of the flowers with their own pollen
was superfluous, as this convolvulus is highly self-fertile; but I acted
in this manner to make the experiments correspond in all respects.
Whilst the flowers are young the stigma projects beyond the anthers; and
it might have been thought that it could not be fertilised without the
aid of humble-bees, which often visit the flowers; but as the flower
grows older the stamens increase in length, and their anthers brush