Flowers legitimately fertilised set seeds under conditions which cause the
almost complete failure of illegitimately fertilised flowers. Thus in the spring
of 1862 forty flowers were fertilised at the same time in both ways. The plants
were accidentally exposed in the greenhouse to too hot a sun, and a large number
of umbels perished. Some, however, remained in moderately good health, and on
these there were twelve flowers which had been fertilised legitimately, and
eleven which had been fertilised illegitimately. The twelve legitimate unions
yielded seven fine capsules, containing on an average each 57.3 good seeds;
whilst the eleven illegitimate unions yielded only two capsules, of which one
contained 39 seeds, but so poor, that I do not suppose one would have
germinated, and the other contained 17 fairly good seeds.
From the facts now given the superiority of a legitimate over an illegitimate
union admits of not the least doubt; and we have here a case to which no
parallel exists in the vegetable or, indeed, in the animal kingdom. The
individual plants of the present species, and as we shall see of several other
species of Primula, are divided into two sets or bodies, which cannot be called
distinct sexes, for both are hermaphrodites; yet they are to a certain extent
sexually distinct, for they require reciprocal union for perfect fertility.
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