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It is probable that an accessory cross-fertilization frequently results from a mass of the pollen falling directly upon the stigma of a neighboring blossom, or even upon its own stigma, but even in the latter case, as has been absolutely demonstrated as a general law by the experiments of Darwin, the pollen from a separate flower is almost invariably prepotent, and leads to the most perfect fruition, and thus to the survival of the fittest the cross-fertilized.
The homing Bee has her honey in her crop and her pollen on her leg-brushes: the first is inaccessible to the thief; the second is powdery and would give no resting-place to the egg. Besides, there is not enough of it yet: to collect the wherewithal for that round loaf of hers, the Bee will have to make repeated journeys.
But a serious cause of error seems to me to be here introduced: a plant to be hybridised must be castrated, and, what is often more important, must be secluded in order to prevent pollen being brought to it by insects from other plants. Nearly all the plants experimentised on by Gartner were potted, and apparently were kept in a chamber in his house.
The air was cold for all the sun shone, the smell of catkin pollen, bursting buds, and the odour of earth steaming in the sun, was in every breath; the blackbirds were calling, and the doves; the ganders looked longingly at the sky and screamed a call to every passing wild flock, and Deams' rooster wanted to fight all creation, if you judged by the boasting he was doing from their barnyard gate.
One end, from opening, was 2 5-8, containing three cells, two with larva and pollen, the third empty. I think this was the work of one bee, and, as near as I can judge, about twenty-five days' work. Width of tunnel inside at widest 9-16 inch.
Blackley gives two tables, showing the average number of pollen grains collected in twenty-four hours on one square of glass, between May 28 and August 21, in both a rural and an urban position. The maximum both in town and country was reached on June 28, when in the town 105 pollen grains were deposited, and in the country 880 grains.
Each of these exhaled its own salubrious springlike perfume, and a light cloud of pollen, which covered the eyelashes and hair of the young girl with a delicate white powder. "Here, Pere Theotime," said she, handing her collection over to the master charcoal-dealer, "I gathered these for you to ornament the roof of your dwelling."
When a bee so charged gets into another bucket, or into the same bucket a second time, and has to crawl out, he brushes against the stigma, and leaves the pollen on it.
Blackley's first experiment gave as a result that 104 pollen grains were deposited in the glass attached to the kite, while only 10 were deposited on a glass near the ground. This experiment was repeated. Again and again, and always with the same result, there was more pollen in the upper strata of the air than in the lower. A very interesting experiment was performed at Filey, in June, 1870.
But it is the opinion of most physiologists that there is no essential difference between a bud and an ovule in their earliest stages of formation; so that, in fact, "sports" support my view, that variability may be largely attributed to the ovules or pollen, or to both, having been affected by the treatment of the parent prior to the act of conception.
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