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Updated: June 29, 2025
Both parents bear large capsules with an abundance of seed, but in the hybrids the capsules remain narrow and weak, ripening not more than one-tenth the usual quantity of seed. Both parents are easily cultivated in annual generations and the same holds good for the hybrid.
On the contrary, brothers and sisters have usually been crossed in each successive generation, in opposition to the constantly repeated admonition of every breeder. And in this case, it is not at all surprising that the inherent sterility in the hybrids should have gone on increasing.
Finally, looking to all the ascertained facts on the intercrossing of plants and animals, it may be concluded that some degree of sterility, both in first crosses and in hybrids, is an extremely general result; but that it cannot, under our present state of knowledge, be considered as absolutely universal.
Gartner further admits that hybrids between very closely allied species are more variable than those from very distinct species; and this shows that the difference in the degree of variability graduates away.
They then take to flight, at first slowly, but afterwards with the swiftness of the roe; while the male, true to his trust, hangs in the rear, and halts at intervals, as if to cover the retreat of the herd. The llama, guanaco, alpaco, and vicuna, although different species, will breed with each other; and it is certain that some of their hybrids will again produce young.
Moreover, whenever complicated experiments are in progress, so careful an observer as Gartner would have castrated his hybrids, and this would have insured in each generation a cross with pollen from a distinct flower, either from the same plant or from another plant of the same hybrid nature.
Another objection, notwithstanding the great stress often laid on it, seems to me to be altogether beside the real issue. It is the one derived from the invariable sterility, real or supposed, of hybrids. A fact cited by Mr.
We will now consider a little more in detail the circumstances and rules governing the sterility of first crosses and of hybrids. Our chief object will be to see whether or not the rules indicate that species have specially been endowed with this quality, in order to prevent their crossing and blending together in utter confusion.
But it harmonises perfectly with the view that there is no essential distinction between species and varieties. First crosses between forms sufficiently distinct to be ranked as species, and their hybrids, are very generally, but not universally, sterile.
But after all, the cause more probably lies in some imperfection in the original act of impregnation, causing the embryo to be imperfectly developed, rather than in the conditions to which it is subsequently exposed. In regard to the sterility of hybrids, in which the sexual elements are imperfectly developed, the case is somewhat different.
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