What substratum of plain truth underlies the doctrine of the metamorphoses of plants? Botanists would agree that all sporophylls, however modified, are homologous or answerable parts. Carpels and stamens are no doubt modified sporophylls. Petals are sometimes, perhaps always, modified stamens, and therefore modified sporophylls also. We must not call a sporophyll a _leaf_, for it contains a sporangium of independent origin, and the sporangium is the more essential of the two. The common origin of foliage-leaf, bract, perianth-leaf, sporophyll (apart from the sporangium), and seed-leaf is unshaken. We may picture to ourselves a plant clothed with nearly similar leaves, some of which either bear sporangia or else lodge sporangia in their axils. Part of such a primitive flowering plant might retain its vegetative function and become a leafy shoot, while another part, bearing crowded sporophylls, might yield male, female, or mixed cones. From an ancestor thus organised any flowering plant might be derived. But the chief wonder of the theory of Metamorphoses—viz., the derivation of stamen and pistil from mere foliage-leaves—disappears. Anther and ovule take their real origin from the sporangium, whose supporting leaf is only an accessory. The chief steps by which the morphology of the flowering plant has been attained are these:—Cesalpini (1583), followed by several other early botanists, recognized the fundamental identity of foliage-leaf, perianth-leaf, and seed-leaf. Linnæus (1759) added stamen and carpel to the list, identifications of greater interest, but only partially defensible. Wolff (1759) justified by similarity of development the recognition of floral organs as leaves. Goethe (1790) traced structural similarity, transitions, and retrogression in leaves of diverse function. Hofmeister (1849-57) showed a relationship between the flowering plant and the higher cryptogams. Oliver and Scott (1904), inheriting the results of Williamson's work, discovered a carboniferous seed-bearing plant, one of a large group intermediate between ferns and cycads. It is now possible to explain the resemblance of the various leaf-like appendages of the flowering plant by derivation either from the leaves or the sporophylls (the latter not being wholly leaves) of some extinct cryptogam, which was either a fern or a near ally of the ferns. Early Notions about the Lower Plants.