with their own pollen; and as the pollen is mature
and shed long before the stigma of the same flower
is ready for fertilisation, it was necessary to number
each flower and keep its pollen in paper with a corresponding
number. By this means well-matured pollen was
used for self-fertilisation. Several flowers
on the same plant were crossed with pollen from a distinct
individual, and to obtain this the conjoined anthers
of young flowers were roughly squeezed, and as it
is naturally protruded very slowly by the growth of
the pistil, it is probable that the pollen used by
me was hardly mature, certainly less mature than that
employed for self-fertilisation. I did not at
the time think of this source of error, but I now
suspect that the growth of the crossed plants was thus
injured. Anyhow the trial was not perfectly fair.
Opposed to the belief that the pollen used in crossing
was not in so good a state as that used for self-fertilisation,
is the fact that a greater proportional number of
the crossed than of the self-fertilised flowers produced
capsules; but there was no marked difference in the
amount of seed contained in the capsules of the two
lots. (5/24. Gartner has shown that certain plants
of Lobelia fulgens are quite sterile with pollen from
the same plant, though this pollen is efficient on
any other individual; but none of the plants on which
I experimented, which were kept in the greenhouse,
were in this peculiar condition.)
As the seeds obtained by the above two methods would
not germinate when left on bare sand, they were sown
on the opposite sides of four pots; but I succeeded
in raising only a single pair of seedlings of the same
age in each pot. The self-fertilised seedlings,
when only a few inches in height, were in most of
the pots taller than their opponents; and they flowered
so much earlier in all the pots, that the height of
the flower-stems could be fairly compared only in
Pots 1 and 2.
Table 5/70. Lobelia fulgens (First Generation).
Heights of flower-stems measured in inches.
Column 1: Number (Name) of Pot.
Column 2: Height of Flower-stems on the Crossed
Plants.
Column 3: Height of Flower-stems on the Self-fertilised
Plants.
Pot 1 : 33 : 50.
Pot 2 : 36 4/8 : 38 4/8.
Pot 3 : 21* : 43.
Pot 4 : 12* : 35 6/8.
Not in full flower.
The mean height of the flower-stems of the two crossed
plants in Pots 1 and 2 is here 34.75 inches, and that
of the two self-fertilised plants in the same pots
44.25 inches; or as 100 to 127. The self-fertilised
plants in Pots 3 and 4 were in every respect very much
finer than the crossed plants.