We have taken only a few examples, but the same is undoubtedly true of all Taxonomic groups _above species_. Passing over these last for the moment, we take next _races_ and _varieties_. These smaller groups are admitted by all to be formed by a natural process, because not only can we make them artificially, but all the intermediate links may be found in Nature. So we have only _species_ remaining. Yes; species are imagined by the old-school naturalist and by the anti-evolutionist of to-day as the _ultimate elements_ of Taxonomy. This, then, is the _last ditch_ upon which the defense of supernaturalism in the realm of Nature is made. “Other groups,” they say, “may have gradually become what they now are by the successive introduction of specific forms according to a preordained plan which is well expressed by the formal laws of evolution. But _species_ are without transition forms. _They_ come in suddenly, remain unchanged while they continue, and finally pass out suddenly, so far as specific characters are concerned. New species come in their places by direct act of creation--by _substitution_, not by transmutation.” This, then, is the last intrenchment. Can we give any good evidence of gradual formation of species? I believe we can. First, then, it is admitted that we can easily make varieties and races artificially. We will not _now_ describe the process; we are all familiar with the results, viz., the varieties of domestic animals and of useful and ornamental plants; the extremely different breeds of horses, cattle, sheep, dogs, pigeons, etc.; of wheat, cabbages, turnips; of roses, dahlias, etc., etc. No one will doubt that the extreme varieties of any of these, say greyhound and pug, if wild, would be called distinct species, or even distinct genera. We do not call them so, for two reasons: first, because we see them made; and, second, because we find all intermediate links between them; and the usual definition of species is that they can not be made, and they have no intermediate links. Thus, then, the question is narrowed down to _wild species_. They say: “We take our stand on these” (surely a very narrow ground for so broad a philosophy). “We defy you to show gradual formation with intermediate links.”