Clearly then, a hybrid plant is one that has sprung from the union of two half-cells, one of which bore the Dominant traits of one parent, while the other bore the Recessive traits of the other parent. But because Dominant traits overpower Recessive traits in development, the cross between a tall plant and a dwarf plant produces tall offspring only—Tallness being a Dominant trait which overpowers the Recessive trait of Dwarfness. So too, the cross between a plant bearing coloured and a plant bearing white flowers produces offspring bearing coloured flowers only—Colour being Dominant over the Recessive Trait of Whiteness.
But because the Recessive traits of Dwarfness and of Whiteness were only overpowered in the plant-development, by the Dominant traits of Tallness and Colour, but were neither lost nor impaired in stock, hybrid plants that had shown only Dominant traits in growth and constitution, produce, nevertheless, two sorts of sex-cells for plant-reproduction: cells that bear the Recessive traits of the one parent, and cells that bear the Dominant traits of the other parent. So that in the fertilisation of one another by such hybrids, cells bearing Dominant traits mate with other cells bearing Dominant traits, and produce plants of pure Dominant type—Tall or Coloured, like one of the grandparents. While cells bearing Recessive traits mate with other cells bearing Recessive traits, and produce plants of pure Recessive type—Dwarf or White, like the other grandparent.
It is seen, therefore, that in plants, when a cell bearing Dominant traits mates with one bearing Recessive traits, the Dominant characteristics so overpower the Recessive that these latter lie latent, and concealed, in the resulting plant. But when a cell bearing Recessive traits mates with another cell bearing Recessive traits, the resulting plant (its growth and development not over-ridden now by the more assertive Dominant traits) is able to develop its Recessive characteristics.
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These interesting and significant laws of plant-heredity and constitution, discovered by Mendel in peas, have since been found by many expert observers to hold true as regards other species of plants; as too in poultry, in mice, and in rabbits, and moreover, in the hereditary transmission of human characteristics.
In Heredity and Variation, Dr. Saleeby points out that in the mating of a black with a white rabbit, some of the offspring will be black like one parent, some white like the other, and some grey—a blend of the colours of both parents.
In the last case, the Dominant trait of Blackness, derived from one rabbit-parent, blends in the fur of the rabbit-offspring with the Recessive trait of Whiteness, derived from the other rabbit-parent; a grey rabbit resulting. But that the Contrasted Traits come to no more than a temporary and partial compromise during the life of such a rabbit-individual, without either of the traits losing its intrinsic characteristic—Blackness and Whiteness, respectively—is proved by the fact that these grey rabbit-offspring, on further breeding, produce not grey rabbits, but black rabbits and white rabbits; proving that the Black trait and the White trait in them remained distinct and segregated, neither altering its character in the least degree.
It is as though one should take a spoonful of black pepper and a spoonful of white salt, and thoroughly mix them. A drab "pepper-and-salt" mixture will result. But neither pepper nor salt will have changed its colour or its properties one iota. Could they be separated out again, each would be precisely as it had been before mixing. So it is with the Dominant and the Recessive traits in living organisms. They commingle intimately, but each retains its original and intrinsic quality.
All the diverse and beautiful varieties of vegetation and the loveliness of flowers, in form and colour, result from multiple associations in hybrid-plants, of those which are known as the "Contrasted Traits" of parent-stock.
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