Short-styled by pollen of long-styled. Legitimate union:
8 : 7 : 75 : 48 : 65.0.

Short-styled by own-form pollen. Illegitimate union :
18 : 7 : 43 : 5 : 18.8 (This average is perhaps rather too low).

SUMMARY:

The two legitimate unions together :
20 : 18 : 77 : 47 : 66.0.

The two illegitimate unions together :
39 : 21 : 66 : 5 : 35.5 (This average is perhaps rather too low).

We may infer from this table that the fertility of the two legitimate unions
taken together is to that of the two illegitimate unions together, as judged by
the proportional number of flowers which when fertilised in the two methods
yielded capsules, as 100 to 60. If we judge by the average number of seeds per
capsule produced by the two kinds of unions, the ratio is as 100 to 54; but this
latter figure is perhaps rather too low. It is surprising how rarely insects can
be seen during the day visiting the flowers, but I have occasionally observed
small kinds of bees at work; I suppose, therefore, that they are commonly
fertilised by nocturnal Lepidoptera. The long-styled plants when protected from
insects yield a considerable number of capsules, and they thus differ remarkably
from the same form of the cowslip, which is quite sterile under the same
circumstances. Twenty-three spontaneously self-fertilised capsules from this
form contained, on an average, 19.2 seeds. The short-styled plants produced
fewer spontaneously self-fertilised capsules, and fourteen of them contained
only 6.2 seeds per capsule. The self-fertilisation of both forms was probably
aided by Thrips, which abounded within the flowers; but these minute insects