. The Eusporangiatae; the comparative morphology of the Ophioglossaceae and Marattiaceae. Ophioglossaceae; Marattiaceae. THE GAMETOPHYTE 127 layers of cells. The form and division of the apical cells is exactly the same as in the other Marattiaceae. Stiff brown rhizoids are developed upon the lower surface and are mainly confined to the midrib, over which they may be evenly distributed, or there may be certain regions of considerable extent which are quite destitute of them. The rhizoids in all the species which have yet been examined are truly multicellular, as was correctly shown by Brebner
. The Eusporangiatae; the comparative morphology of the Ophioglossaceae and Marattiaceae. Ophioglossaceae; Marattiaceae. THE GAMETOPHYTE 127 layers of cells. The form and division of the apical cells is exactly the same as in the other Marattiaceae. Stiff brown rhizoids are developed upon the lower surface and are mainly confined to the midrib, over which they may be evenly distributed, or there may be certain regions of considerable extent which are quite destitute of them. The rhizoids in all the species which have yet been examined are truly multicellular, as was correctly shown by Brebner to be the case in D. simplicifolia. The nuclei are not very large, but can be readily demonstrated. The distribution of the reproductive organs is not always the same. Apparently the usual course of development is present here, the antheridia appearing first upon the lower side of the midrib and the adjacent points of the prothallium; later, nearer the apex and upon the lower side, the archegonia arise. Sometimes, how- ever, as in the other forms, there is a more or less marked tendency to dioecism and some of the smaller prothallia seem to bear only archegonia or antheridia, and it is common to find antheridia developing exclusively upon the lateral lobes, which. Fig. 96.—Kaulfussia. A. Section of a young prothallium, showing two antheridia on the ventral side (reversed in the figure). X80. B-E. Longitudinal sections of antheridia. F-H. Transverse sections. G, H are surface views showing the opercular cell, m, mantle cells. X 180. I. Cell from interior of prothallium, showing the endophyte. apparently never produce archegonia at all. Antheridia may also occur upon the upper surface, but this is not common, and in no cases were archegonia seen except upon the lower surface of the midrib. The reproductive organs are sometimes found in great numbers upon the older prothallia, the whole lower surface of the midrib being beset with archegonia. Quite as often, however, extensive a
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