Part 2
methods, but in the full-grown spermatozoid within the antheridium the nuclear origin of all but the extreme forward end was unmistakable. Perhaps, as Stras- burger claims, the cilia-bearing part is cytoplasmic and the cilia are direct outgrowths of this part, but this point was not satisfactorily proven. The origin of the antheridium, as well as its development and its complete immersion in the prothallium, have their nearest approach in Equisetum. The species of Lycopodium investigated by Treub® also show a good deal of resemblance. Among the ferns, from what is known, the Ophioglosseae show a close resemblance, but the development of the antheridium is too imperfectly known to allow of a satisfactory comparison. The antheridium of Osmunda is in some degree intermediate between that of Marattiaceae and the more specialized Leptosporangiatae. THE ARCHEGONIUM. The archegonia seem to be confined to the lower side of the midrib, and are formed some distance behind the growing- point of the prothallium. So far as could be determined, any superficial cell of the apical meristem can develop into an archegonium. The succession of divisions seem to correspond exactly with those of the other ferns. The mother-cell divides usually into three superimposed cells (Fig. 13), of which the lowest, J, usually divides several times by vertical walls and forms the base of the archegonium. From the central one, by transverse divisions are formed the canal-cells and egg, ' Loc. cit. p. 106. ? Belajeff, Ber. der Deutschen Bot. Gesellschaft, Dec. 1889. * Annals of the Botanical Garden, Buitenzorg, Vols. iv, v, vii.