Comparative Morphology of Dumortiera hirsuta

1. Dumortiera hirsuta, probably one of two species only of this genus, is widely distributed in the tropics of both hemispheres and also in the more humid and warmer regions of the temperate zones. 2. The carpocephalum is covered with hairlike appendages and is borne on a stalk which has two groups of rhizoids on the side which corresponds to the ventral side of the thallus, this feature being the only suggestion of dorsiventrality in the stalk. 3. One or two sporophytes in each of the average number of eight groups of archegonia come to maturity. The sporophyte is made up of a rather indistinctly anchor-like foot, a massive columnar seta, and an ovate capsule which is depressed at the basal end. The whole is incased in a calyptra which is six cells in thickness. 4 The spores are ripe in Florida about the middle of April. They are viable for but a short time after the dehiscence of the capsule. The ripe spore is somewhat trihedral in form, is about 30 μ in its longest axis, and is surrounded by a golden brown papillate exine. 5. The elaters of Dumortiera resemble those of Marchantia in structure, size, and color; the proportionate number of spores and elaters agrees well with the condition in Marchantia domingensis. 6. The spores of Dumortiera germinate within six or seven days after being sown on a liquid medium. The first step in germination, following a considerable distention of the spore, is usually the emergence of a rhizoid followed by the formation of a bud from the spore. 7. The budding process most often continues until a short filament of three or four cells is formed. In the short filament of cells, divisions at the tip, usually in an oblique plane, result in the establishment of a wedge-shaped apical cell of the fern type. This zigzag type of cell production continues and may occur in every cell, the original cell only being excepted, as growth advances. 8. The young sporelings of Dumortiera are remarkably like those of Onoclea, a typical Polypodiaceae, throughout the germination process and in the early stages of the development of the young gametophyte. 9. The adult thallus shows no lacunae and there is no definite line of demarcation between the chlorophyllose and the colorless cells, which latter are found in the more or less central part of the thallus; and there are no ventral scales on the thallus of Dumortiera. 10. Dumortiera may be considered an aberrant species because of the relative simplicity of the gametophyte; and the primitive