Table 9/G gives the relative fertility of flowers on crossed plants
again cross-fertilised, and of flowers on self-fertilised plants again
self-fertilised, either in the first or in a later generation. Here two
causes combine to diminish the fertility of the self-fertilised flowers;
namely, the lesser efficacy of pollen from the same flower, and the
innate lessened fertility of plants derived from self-fertilised seeds,
which as we have seen in the previous Table 9/D is strongly marked. The
fertility was determined in the same manner as in Table 9/F, that is, by
the average number of seeds per capsule; and the same remarks as before,
with respect to the different proportion of flowers which set capsules
when they are cross-fertilised and self-fertilised, are here likewise
applicable.
TABLE 9/G.--RELATIVE FERTILITY OF FLOWERS ON CROSSED AND SELF-FERTILISED
PLANTS OF THE FIRST OR SOME SUCCEEDING GENERATION; THE FORMER BEING
AGAIN FERTILISED WITH POLLEN FROM A DISTINCT PLANT, AND THE LATTER AGAIN
WITH THEIR OWN POLLEN. FERTILITY JUDGED OF BY THE AVERAGE NUMBER OF
SEEDS PER CAPSULE. FERTILITY OF CROSSED FLOWERS TAKEN AS 100.
Column 1: Name of plant and feature observed.
Column 2: x, in the expression, 100 to x.
Ipomoea purpurea--crossed and self-fertilised flowers on the crossed and
self-fertilised plants of the first generation yielded seeds as: 93.
Ipomoea purpurea--crossed and self-fertilised flowers on the crossed and
self-fertilised plants of the 3rd generation yielded seeds as: 94.
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