I have as yet spoken as if the varieties of the same species were invariably fertile when intercrossed. But it is impossible to resist the evidence of the existence of a certain amount of sterility in the few following cases, which I will briefly abstract.
Natural Selection or the Survival of the Fittest
Several writers have misapprehended or objected to the term Natural Selection. Some have even imagined that natural selection induces variability, whereas it implies only the preservation of such variations as arise and are beneficial to the being under its conditions of life.
Sexual Selection
No one objects to agriculturists speaking of the potent effects of man’s selection; and in this case the individual differences given by nature, which man for some object selects, must of necessity first occur.
Illustrations of the Action of Natural Selection, or the Survival of the Fittest
In the literal sense of the word, no doubt, natural selection is a false term; but who ever objected to chemists speaking of the elective affinities of the various elements?—and yet an acid cannot strictly be said to elect the base with which it in preference combines.
Intercrossing of Individuals
Every one knows what is meant and is implied by such metaphorical expressions; and they are almost necessary for brevity. So again it is difficult to avoid personifying the word Nature; but I mean by nature, only the aggregate action and product of many natural laws, and by laws the sequence of events as ascertained by us.
- You hit me with a cricket bat.
- You know how I sometimes have really brilliant ideas?
- I’m nobody’s taxi service; I’m not gonna be there to catch you every time you feel like jumping out of a spaceship.
Turning for a brief space to animals: various terrestrial species are hermaphrodites, such as the land-mollusca and earth-worms; but these all pair. As yet I have not found a single terrestrial animal which can fertilise itself.
- You hit me with a cricket bat.
- Aw, you’re all Mr. Grumpy Face today.
- *Insistently* Bow ties are cool! Come on Amy, I’m a normal bloke, tell me what normal blokes do!