Page:Evolution of Life (Henry Cadwalader Chapman, 1873).djvu/134

96 found in the same spore-case, but in the Salvinia and Azolla the large and small spores have their special spore-cases, as in the Lycopodiaceae; the large spore alone develops the Prothallus with Archegonia and embryo-cells, the small spores alone producing Antheridia with spiral filaments. The reproduction, however, of the Horse-tail, Fern, Rhizocarp, or Lycopod is always due to the contact of the spiral filament of the Antheridium with the embryo-cell of the Archegonium, the new plant growing always from a Prothallus. The Lycopodiaceae appeared on the earth later than the Ferns, and have probably come from them, being closely related at the present time by intermediate forms (Opioglossae). The Rhizocarpae may be regarded as aquatic Lycopods. The structure of the stem and reproductive apparatus, and the form of the embryo, are striking proofs of the truth of the view that the Lycopodiaceae are the intermediate forms, the links uniting the Flowerless and Flowering plants. The importance of the facts just mentioned will be better appreciated when the Lycopodiaceae are compared with the simplest of flowering plants. We leave now the Flowerless plants, or Cryptogamia, and turn to the Flowering plants, or Phanerogamia.