_Environment_, _evolution_, _development_, _instinct_, _species_, _spontaneous_, _variation_ are some of the more important words, whose modern meanings, if we look at their semantic history, are found to bear the unmistakable stamp of Darwinism, and we ought perhaps to add _ooze_[59] and _slime_.[59] To Darwin we should have to attribute the tendency of _evolution_ to lose its etymological suggestion of a vegetable growth, an unfolding from the centre outwards. _Species_ (Latin ‘species’, ‘form’ or ‘appearance’) was used by Cicero to translate Plato’s “Idea” (Chapter VI). It held an important place in the logic of the Middle Ages as one of the five “predicables” by which an object could be defined, and for centuries its biological meaning was only one among many. This particular interpretation did not begin to come into prominence until the eighteenth century, when Addison, for instance, used the phrase “the species” of the human race; but since Darwin published his _Origin of Species_ (in which the word is, of course, given an exclusively biological sense) it has, for the ordinary man, had practically no other. It is interesting to observe that here again, as the words are commonly employed, the Latin form has grown more concrete and the Greek more abstract and intellectual. But the change did not confine itself to such technical words as these. One has only to pick up a journalistic article on almost any subject and read it, endeavouring to let the words mean only what they did a hundred years ago, to see how the whole scheme of Natural Selection can lurk unseen, but not unfelt, behind some colourless little word like _adapt_, _competition_, _gregarious_, _modification_, _protective_, _selection_, and even _animal_, _facts_, _law_, _life_, _man_, _Nature_,... Or we can see it in the curious, absolute use of the word _fit_, in the sense of ‘physically healthy’, which, appearing first in the seventies, is obviously due to the famous phrase, the “survival of the fittest” (i.e. the fittest to survive in a struggle for existence). How modern the new meanings are may be gauged by the fact that the word _heredity_, the basic principle of modern natural scientific theory, is recorded by Francis Galton as having been considered “fanciful and unusual” in 1859, while _atavism_ first appears in 1833.