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The sterility of hybrids is a very different case from that of first crosses, for their reproductive organs are more or less functionally impotent; whereas in first crosses the organs on both sides are in a perfect condition.
The appearance of the stripes is not accompanied by any change of form, or by any other new character. We see this tendency to become striped most strongly displayed in hybrids from between several of the most distinct species. When the oldest and truest breeds of various colours are crossed, we see a strong tendency for the blue tint and bars and marks to reappear in the mongrels.
There have been marriages and intermarriages, some good matches and some bad ones, some with vigorous and some with sickly offspring, and some hybrids of such monstrous malformation as almost to make us fear that a new style can be invented. But the effect is impossible without the cause. Save the mysterious Pyramids, every structure extant acknowledges its ancestry.
That their fertility, besides being eminently susceptible to favourable and unfavourable conditions, is innately variable. That it is by no means always the same in degree in the first cross and in the hybrids produced from this cross. That the fertility of hybrids is not related to the degree in which they resemble in external appearance either parent.
Moreover it will contain seeds originated by the spontaneous but numerous crosses of the true plants with the sparsely intermingled hybrids. This brings us to the question, as to what will be the visible consequences of the occurrence of such invisible hybrids in the following generation. In opposition to the direct effects just described, we may call them indirect.
Having given this long list of examples of the rule of the dominancy of the active character over the opposite dormant unit, the question naturally arises as to how the antagonistic units are combined in the hybrid. This question is of paramount importance in the consideration of the offspring of the hybrids.
In regard to the sterility of hybrids in successive generations; though Gärtner was enabled to rear some hybrids, carefully guarding them from a cross with either pure parent, for six or seven, and in one case for ten generations, yet he asserts positively that their fertility never increased, but generally greatly decreased.
We can fight foreigners when the time comes. He directed Nevil to look home, and cast an eye on the cotton-spinners, with the remark that they were binding us hand and foot to sell us to the biggest buyer, and were not Englishmen but 'Germans and Jews, and quakers and hybrids, diligent clerks and speculators, and commercial travellers, who have raised a fortune from foisting drugged goods on an idiot population.
"If rose-combed fowl were mated with single-combed fowl, the offspring were all rose-combed, but when these rose-combed fowl were mated, the offspring were again rose-combed and single-combed.... If gray rabbits were mated with black rabbits, their hybrids were all gray, the black seemingly disappearing, but when the second generation were mated, the progeny were again grays and blacks."
In either case, then, whether with hybrids or in cases of parthenogenesis, the early death of the embryo is due to inability to recollect, owing to a fault in the chain of associated ideas. All the facts here given are an excellent illustration of the principle, elsewhere insisted upon by Mr.
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