5 : 61 : 6.
If we compare the figures in this table with those given in the first chapter,
showing the normal fertility of the common primrose, we shall see that the
illegitimate purple- and yellow-flowered varieties are very sterile. For
instance, 72 flowers were fertilised with their own pollen and produced only 11
good capsules; but by the standard they ought to have produced 48 capsules; and
each of these ought to have contained on an average 52.2 seeds, instead of only
11.5 seeds. When these plants were illegitimately and legitimately fertilised
with pollen from the common primrose, the average numbers were increased, but
were far from attaining the normal standards. So it was when both forms of the
common primrose were fertilised with pollen from these illegitimate plants; and
this shows that their male as well as their female organs were in a deteriorated
condition. The sterility of these plants was shown in another way, namely, by
their not producing any capsules when the access of all insects (except such
minute ones as Thrips) was prevented; for under these circumstances the common
long-styled primrose produces a considerable number of capsules. There can,
therefore, be no doubt that the fertility of these plants was greatly impaired.
The loss is not correlated with the colour of the flower; and it was to
ascertain this point that I made so many experiments.
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