Many of the crossed seedlings, on the
other hand, survived; and some twined up the stems of the Iberis to the
height of 11 inches. These cases prove that the crossed seedlings have
an immense advantage over the self-fertilised, both when growing
isolated under very unfavourable conditions, and when put into
competition with each other or with other plants, as would happen in a
state of nature.
CROSSED AND SELF-FERTILISED PLANTS OF THE FOURTH GENERATION.
Seedlings raised as before from the crossed and self-fertilised plants
of the third generation in Table 2/3, gave results as follows:--
TABLE 2/5. Ipomoea purpurea (Fourth Generation).
Heights of Plants in inches:
Column 1: Number (Name) of Pot.
Column 2: Crossed Plants.
Column 3: Self-fertilised Plants.
Pot 1 : 84 : 80.
Pot 1 : 47 : 44 1/2.
Pot 2 : 83 : 73 1/2.
Pot 2 : 59 : 51 1/2.
Pot 3 : 82 : 56 1/2.
Pot 3 : 65 1/2 : 63.
Pot 3 : 68 : 52.
Total : 488.5 : 421.0.
Here the average height of the seven crossed plants is 69.78 inches, and
that of the seven self-fertilised plants 60.14; or as 100 to 86. This
smaller difference relatively to that in the former generations, may be
attributed to the plants having been raised during the depth of winter,
and consequently to their not having grown vigorously, as was shown by
their general appearance and from several of them never reaching the
summits of the rods.
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