We must not forget, in addition, that, in a state of Nature, selection is neither for one feature, nor is it pedigree selection, or breeding from the fittest.
It is the extermination of the unfit, and unfitness may come from the imperfect co-ordination of the whole, or from defect in any quality whatever.
It is undoubtedly true that many of our domesticated races can be proved to have arisen as "sports," and that no great change of type can be effected, by the methods of the breeder, without sports; but there seem to be both evidence and theoretical ground for holding that, in this particular, artificial selection furnishes no measure of natural selection.
It seems to me that, notwithstanding the great value of Galton's data, they fail to prove that the "principle of organic stability" owes its existence to anything except past selection; that regression to mediocrity occurs when ancestry is studied uncomplicated by nurture; that the "mid-parent" is anything else than the actual parent; that "sports" are fundamentally different from the ordinary differences between individuals; or that natural selection is restricted to the preservation of sports.
Our tendency to believe that a type is something more real and substantial than the transitory phenomena which exhibit it is deeply rooted in our minds.
As the very nature of this belief renders disproof of it impossible, we can feel little surprise at its appearance and reappearance time after time in the history of thought, although science is based upon the well-warranted opinion that, whether types are real or unreal, we know them only as generalizations or abstractions constructed by our minds out of our experience of the orderly sequence of phenomena.
In zoölogy and botany the conception of species is unquestionably valid and justifiable, and as its most obvious characteristic is its persistency, as contrasted with the fleeting procession of evanescent individuals, we can not wonder at the vitality of the belief that specific types of life are more real than the individual animals, although Darwin's work has done away with whatever evidence may at one time have seemed to support this belief.
To the further question, whether specific types are inherent in living matter or external and objective to it, Darwin answers that they are both; that they are inherent, insomuch as all their data, or "events," are properties of the physical basis of life; but that they are external, inasmuch as the agreement of the "events" with the "law of frequency of error" is the effect of the environment.
Biology is not a closed science, and Darwin's view of the matter is not proved; possibly it is not provable; but its great