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Darwin, Charles, 1809-1882

"Effects of Cross and Self Fertilisation in the Vegetable Kingdom"

Eleven
pairs were raised and grown in competition in the usual manner; and now
the result was different, for the two lots were nearly equal during
their whole growth. It would therefore be superfluous to give a table of
their heights. When fully grown and measured, the crossed averaged
32.47, and the self-fertilised 32.81 inches in height; or as 100 to 101.
There was no great difference in the number of flowers and capsules
produced by the two lots when both were left freely exposed to the
visits of insects.
PLANTS RAISED FROM BRAZILIAN SEED.
Fritz Muller sent me from South Brazil seeds of plants which were there
absolutely sterile when fertilised with pollen from the same plant, but
were perfectly fertile when fertilised with pollen from any other plant.
The plants raised by me in England from these seeds were examined by
Professor Asa Gray, and pronounced to belong to E. Californica, with
which they were identical in general appearance. Two of these plants
were covered by a net, and were found not to be so completely
self-sterile as in Brazil. But I shall recur to this subject in another
part of this work. Here it will suffice to state that eight flowers on
these two plants, fertilised with pollen from another plant under the
net, produced eight fine capsules, each containing on an average about
eighty seeds. Eight flowers on these same plants, fertilised with their
own pollen, produced seven capsules, which contained on an average only
twelve seeds, with a maximum in one of sixteen seeds.


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