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 areas along 

 the midrib are quite sterile and the archegonia thus appear in patches, separated by 

 sterile intervals. 



THE ENDOPHYTE OF THE MARATTIACE^.. 



In all of the Marattiaceae that I have studied, an endophytic fungus very much 

 Uke that which occurs in the prothallium of the Ophioglossacea; has been found 

 occupying the central cells of the prothallium in nearly all cases. The endophyte 

 which infests the green prothallium of the Marattiaceae, when compared with that 

 found in the strictly saprophytic prothallia of the Ophioglossaceae, shows some 

 differences which are probably not without significance. The structure of the myce- 



