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Groups having the morphological character of species, distinct and permanent races in fact, have been so produced over and over again; but there is no positive evidence, at present, that any group of animals has, by variation and selective breeding, given rise to another group which was, even in the least degree, infertile with the first. Mr.
From the great difficulty of ascertaining the infertility of varieties in a state of nature, for a supposed variety, if proved to be infertile in any degree, would almost universally be ranked as a species; from man attending only to external characters in his domestic varieties, and from such varieties not having been exposed for very long periods to uniform conditions of life; from these several considerations we may conclude that fertility does not constitute a fundamental distinction between varieties and species when crossed.
As soon as the call to arms was issued, these sturdy mountaineers almost to a man abandoned their rocky and infertile fields to the care of their womankind and went to war, utterly regardless of consequences to themselves. During this last absence of four years their homes had fallen into fearful desolation.
During eleven years a record was kept of the number of mares which proved barren or prematurely slipped their foals; and it deserves notice, as shewing how infertile these highly- nurtured and rather closely-interbred animals have become, that not far from one-third of the mares failed to produce living foals.
But between species, in many cases, you cannot succeed in obtaining even the first cross; at any rate it is quite certain that the hybrids are often absolutely infertile one with another. Here is a feature, then, great or small as it may be, which distinguishes natural species of animals.
The fertilization of the ovum in the female is called conception; its growing state is called gestation, and its birth, on becoming a separate being, is called parturition. In its growing condition, and before its birth, the new young life form is known as the foetus. How this is brought about is substantially as follows: As already stated, the infertile ovum, or egg, is produced by the woman.
Eden Place was a short street running at right angles with Eden Square, a most unattractive and infertile triangle of ground in a most unattractive but respectable quarter of a large city. It was called a square, not so much, probably, because it was triangular in shape, as because it was hardly large enough to be designated as a park.
The colonist of the eighteenth century a merchant, a farmer, or a fur trader thought that Cape Breton was bleak and infertile and refused to settle there. Louisbourg remained a compact fortress with a good harbor, free from ice during most of the year, but too much haunted by fog. It looked out on a much-traveled sea. But it remained set in the wilderness.
I have had equally good results, however, with one male to 20 hens. In the Little Compton and South Shore districts, one male is used for thirty or even forty hens. By infertile eggs is meant eggs in which the sperm cell has never united with the ovum.
Darwin in which mongrel animals, descended from the same undoubted species, have been persistently infertile inter se; nor any clear case in which hybrids between animals, generally admitted to be distinct species, have been continuously fertile inter se.
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