of another species?  And who that is convinced of this can long undoubtingly hold the original distinctness of turnips from cabbages as an article of faith?  On scientific grounds may not a primordial cabbage or rape be assumed as the ancestor of all the cabbage races, on much the same ground that we assume a common ancestry for the diversified human races?  If all our breeds of cattle came from one stock, why not this stock from the auroch, which has had all the time between the diluvial and the historic periods in which to set off a variation perhaps no greater than the difference between some sorts of cattle?

That considerable differences are often discernible between tertiary individuals and their supposed descendants of the present day affords no argument against Darwin’s theory, as has been rashly thought, but is decidedly in its favor.  If the identification were so perfect that no more differences were observable between the tertiary and the recent shells than between various individuals of either, then Darwin’s opponents, who argue the immutability of species from the ibises and cats preserved by the ancient Egyptians being just like those of the present day, could triumphantly add a few hundred thousand years more to the length of the experiment and to the force of their argument.  As the facts stand, it appears, that, while some tertiary forms are essentially undistinguishable from existing ones, others are the same with a difference, which is judged not to be specific or aboriginal, and yet others show somewhat greater differences, such as are scientifically expressed by calling them marked varieties, or else doubtful species; while others, differing a little more, are confidently termed distinct, but nearly related species.  Now is not all this a question of degree, of mere gradation of difference?  Is it at all likely that these several gradations came to be established in two totally different ways,—­some of them (though naturalists can’t agree which) through natural variation, or other secondary cause, and some by original creation, without secondary cause?  We have seen that the judicious Pictet answers such questions as Darwin would have him do, in affirming, that, in all probability, the nearly related species of two successive faunas were materially connected, and that contemporaneous species, similarly resembling each other, were not all created so, but have become so.  This is equivalent to saying that species (using the term as all naturalists do and must continue to employ the word) have only a relative, not an absolute fixity; that differences fully equivalent to what are held to be specific may arise in the course of time, so that one species may at length be naturally replaced by another species a good deal like it, or may be diversified through variation or otherwise into two, three, or more species, or forms as different as species.  This concedes all that Darwin has a right to ask, all that he can directly infer from evidence.  We must add that it affords a locus standi, more or less tenable, for inferring more.