Could we not explain in this way [mutation] how from two individuals alone the multiplication of the most dissimilar species might have resulted? Their origin would be owing only to certain fortuitous products [chance], in which the elementary particles failed to retain the order they possessed in the father and mother animals; each degree of error would have created a new species; and by dint of repeated divergences there would have come about the infinite diversity of animals that we see today; which will perhaps still increase with time, but to which the passage of centuries will perhaps bring only imperceptible additions.