Primula Sinensis (after Hildebrand) : 100 : 42.
Primula auricula (Scott) : 80 : 15.
Primula Sikkimensis (Scott): 95 : 31.
Primula cortusoides (Scott): 74 : 66.
Primula involucrata (Scott): 72 : 48.
Primula farinosa (Scott): 71 : 44.
Average of the nine species : 88.4 : 61.8.
The fertility of the long-and short-styled plants of the above species of
Primula, when the two forms are fertilised legitimately, and illegitimately with
pollen of the same form taken from a distinct plant, has now been given. The
results are seen in Table 1.12; the fertility being judged by two standards,
namely, by that of the proportional number of flowers which yielded capsules,
and by that of the average number of seeds per capsule. But for full accuracy
many more observations, under varied conditions, would be requisite.
With plants of all kinds some flowers generally fail to produce capsules, from
various accidental causes; but this source of error has been eliminated, as far
as possible, in all the previous cases, by the manner in which the calculations
have been made. Supposing, for instance, that 20 flowers were fertilised
legitimately and yielded 18 capsules, and that 30 flowers were fertilised
illegitimately and yielded 15 capsules, we may assume that on an average an
equal proportion of the flowers in both lots would fail to produce capsules from
various accidental causes; and the ratio of 18/20 to 15/30, or as 100 to 56 (in
whole numbers), would show the proportional number of capsules due to the two
methods of fertilisation; and the number 56 would appear in the left-hand column
of Table 1.
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