The Effects of Cross & Self-Fertilisation in the Vegetable Kingdom · Charles Darwin
SCROPHULARIACEAE, GESNERIACEAE, LABIATAE, ETC.
Some flowers on one of the plants raised from the purchased seeds were fertilised with their own pollen; and others on the same plant were crossed with pollen from a distinct plant. The seeds from twelve capsules thus produced were placed in separate watch-glasses for comparison; and those from the six crossed capsules appeared to the eye hardly more numerous than those from the six self-fertilised capsules. But when the seeds were weighed, those from the crossed capsules amounted to 1.02 grain, whilst those from the self-fertilised capsules were only .81 grain; so that the former were either heavier or more numerous than the latter, in the ratio of 100 to 79.
Text from Project Gutenberg, public domain in the United States.