We may next take the seed itself--the very type of a morphological character. Our fossil record does not go far enough back to tell us the origin of the seed in the Cycadophyta and Pteridosperms (the main line of its development) but some interesting sidelights may be obtained from the Lycopod phylum. In two Palaeozoic genera, as we have seen, seed-like organs are known to have been developed, resembling true seeds in the presence of an integument and of a single functional embryo-sac, as well as in some other points. We will call these organs "seeds" for the sake of shortness. In one genus (Lepidocarpon) the seeds were borne on a cone indistinguishable from that of the ordinary cryptogamic Lepidodendreae, the typical Lycopods of the period, while the seed itself retained much of the detailed structure of the sporangium of that family. In the second genus, Miadesmia, the seed-bearing plant was herbaceous, and much like a recent Selaginella. (See Margaret Benson, "Miadesmia membranacea, a new Palaeozoic Lycopod with a seed-like structure", "Phil. Trans. Royal Soc. Vol." 199, B. 1908.) The seeds of the two genera are differently constructed, and evidently had an independent origin. Here, then, we have seeds arising casually, as it were, at different points among plants which otherwise retain all the characters of their cryptogamic fellows; the seed is not yet a morphological character of importance. To suppose that in these isolated cases the seed sprang into being in obedience to a Law of Advance ("Vervollkommungsprincip"), from which other contemporary Lycopods were exempt, involves us in unnecessary mysticism. On the other hand it is not difficult to see how these seeds may have arisen, as adaptive structures, under the influence of Natural Selection. The seed-like structure afforded protection to the prothallus, and may have enabled the embryo to be launched on the world in greater security. There was further, as we may suppose, a gain in certainty of fertilisation. As the writer has pointed out elsewhere, the chances against the necessary association of the small male with the large female spores must have been enormously great when the cones were borne high up on tall trees. The same difficulty may have existed in the case of the herbaceous Miadesmia, if, as Miss Benson conjectures, it was an epiphyte. One way of solving the problem was for pollination to take place while the megaspore was still on the parent plant, and this is just what the formation of an ovule or seed was likely to secure.