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Updated: June 4, 2025
Every hybridizer knows how unfavourable exposure to wet is to the fertilisation of a flower, yet what a multitude of flowers have their anthers and stigmas fully exposed to the weather! but if an occasional cross be indispensable, the fullest freedom for the entrance of pollen from another individual will explain this state of exposure, more especially as the plant's own anthers and pistil generally stand so close together that self-fertilisation seems almost inevitable.
When the colour is absent from only one of the two upper petals, the nectary is not quite aborted but is much shortened. With respect to the development of the corolla, Sprengel's idea that the ray-florets serve to attract insects, whose agency is highly advantageous, or necessary for the fertilisation of these plants, is highly probable; and if so, natural selection may have come into play.
Thus we are forced to conceive of the determinants in the chromosomes of the fertilised ovum which correspond to the two sides of the body, as entirely distinct from the determinants which cause the condition or 'characters' of the two sides, unless indeed we suppose that determinants of right side with eyes and colour occur in some gametes and of right side without eyes and colour in others, and vice versa, and that homozygous and heterozygous combinations occur in fertilisation.
After fertilisation, the couple, as is rarely found among fish, remain in the neighbourhood of their offspring to assist them if necessary. This praiseworthy sentiment is often the cause of their ruin. The inhabitants of the banks speculate on the love of these fish for their offspring to gain possession of them.
If the conclusion at which he ultimately arrived, that cross fertilisation is favourable to the fertility of the parent and to the vigour of the offspring, is correct, then it follows that all those mechanisms which hinder self-fertilisation and favour crossing must be advantageous in the struggle for existence; and, the more perfect the action of the mechanism, the greater the advantage.
At times, as he felt a warmer puff upon his face, he would raise his eyes from his book, as if to seek whence came this soft caress; but his gaze was vacant, straying without perception over the glowing horizon, over the twisted outlines of that passion-breathing landscape as it stretched out in the sun before him, dry, barren, despairing of the fertilisation for which it longed.
There are a great many animals, from jelly-fishes to fishes and frogs, in which fertilisation is external, and there are no intromittent organs at all. Certain organs on the head and pelvic fins of the Chimaeroid fishes are believed to be used for this purpose. WEAPONS. Organs which are employed in combats between males for the exclusive possession of the females.
Those methods of fertilisation, with which the flower-gardener has in recent years worked such wonders, can undoubtedly be utilised for many objects besides those of the variation of form and hue in ornamental plants.
In 1865, the important bearing of this subject on his theory led Darwin to commence a great series of laborious and difficult experiments on the fertilisation of plants, which occupied him for eleven years, and furnished him with the unexpectedly strong evidence in favour of the influence of crossing which he published in 1876, under the title of "The Effects of Cross and Self Fertilisation in the Vegetable Kingdom."
Commonly the plants are classed as male and female. The males largely predominate. Many horticulturists have sought by the selection of seeds and by artificial fertilisation to control the sex of the plant so that the fruit-bearing females shall be the more numerous, but in vain.
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