At
my request Fritz Muller sent me from Brazil seeds of his self-sterile
plants, from which I raised seedlings. Two of these were covered with a
net, and one produced spontaneously only a single capsule containing no
good seeds, but yet, when artificially fertilised with its own pollen,
produced a few capsules. The other plant produced spontaneously under
the net eight capsules, one of which contained no less than thirty
seeds, and on an average about ten seeds per capsule. Eight flowers on
these two plants were artificially self-fertilised, and produced seven
capsules, containing on an average twelve seeds; eight other flowers
were fertilised with pollen from a distinct plant of the Brazilian
stock, and produced eight capsules, containing on an average about
eighty seeds: this gives a ratio of 15 seeds for the self-fertilised
capsules to 100 for the crossed capsules. Later in the season twelve
other flowers on these two plants were artificially self-fertilised; but
they yielded only two capsules, containing three and six seeds. It
appears therefore that a lower temperature than that of Brazil favours
the self-fertility of this plant, whilst a still lower temperature
lessens it. As soon as the two plants which had been covered by the net
were uncovered, they were visited by many bees,and it was interesting to
observe how quickly they became, even the more sterile plant of the two,
covered with young capsules.
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