The actual geographical distribution of species--any species--does not depend solely on lines of ancestry, however great their persistence of specific characters; nor on any principle of natural selection, nor on the possibility of fertile monstrosities, but on the simple incidence of conditions; and M. De Candolle, in his "Geographie Botanique," virtually concedes this, while treating of geographical considerations in connection with distribution. He in fact says, in so many words, that the actual distribution of species in the past "seems to have been a consequence of preceding conditions." [21] And he is forced to this conclusion by his virtual abandonment of plant-migration, and the alleged means of seed-distribution. The question after all, says Professor Gray, is not "how plants and animals originated, but how they came to exist where they are, and what they are." On only one of these points--that of favoring conditions--can any satisfactory answer be given, except as we defer to the Bible genesis, which explains all. And the reason is, that we can never determine what forms are specific without tracing them back to their origin, and this is impossible. Orders, genera, species, etc., are only so many lines of thought on which we arrange our classifications, just as the parallel wires of an abacus, with their sliding balls, are the lines on which we make our mathematical computations. Agassiz would not allow that varieties existed in nature, except as man's agency effected them, that is, as they were brought about by artificial processes. These artificial processes are quite numerous, and many of them have been practised from remote antiquity. But they seem to have no counterpart in nature, except as insects may contribute to modifications by the distribution of pollen. But all modifications of this character tend towards infertility, while few plants accept any fertilizing aid from other and different species. Any break in their hereditary tendencies, resulting in a metamorphosis that involves the integrity of their stamens and pistils, is stoutly resisted by nature. In considering the question of species, therefore, we should confine our observations to those produced by natural, not artificial, methods; to plants as propagated by the loving tendencies of nature, not by the arbitrary and exacting methods of man--those looking to his gratification only. All these fall into the category, of "nature's bastards," as Shakespeare happily defines them. In view of these considerations, and the new methods of classification, such as grouping genera into families or orders, and these into sub-orders, tribes, sub-tribes, etc., we can readily understand why the great Harvard Professor should have wholly eliminated community of descent from his idea of "species," or hesitated to regard varieties otherwise than as the result of man's agency.