One of the main facts about variation is that it is itself a very variable thing, and the nature of those “fluctuating variations” which are so common in nature well illustrate the point. Within what we know as a species there are many individuals that vary one way or the other from a fairly central, we might almost call them normal, mass of individuals which are typical of that species. Nearly all these forms on the fringe of the species due to the environmental changes and not to changes of hereditary constitution will, if left to themselves, tend through their progeny to become more like the central mass as time goes on, while their position, or some other equally nontypical edge of the fringe, will be taken up by other variants from the average conditions. The amount of this fluctuating variability among plants is beyond calculation, and its action has often been likened to the swinging of a pendulum, which of course spends twice the time passing through the center of its arc, that it does on the limits of it. This very nearly expresses the proportion of fluctuating variants to the mass of typical individuals in many species of plants. In many others, often peculiarly unstable species, the number of individuals at the fringe is very large indeed. Sometimes there may be one or more that do hold their characteristics, in which case we know that they are not true environmental variations but have actually a different constitution. These will be considered presently under another and different sort of variability. But, speaking generally, these fluctuating or environmental variants are merely forms of the species, and, other things being equal, they will not actually originate new species.