24 



THE OPHIOGLOSSALES 



antheridium is but one cell in thickness, and I have verified this for both of the 

 species under consideration. 



The first wall to be formed in the cover cell is a nearly median one and vertical 

 (fig. 12, B), and this is followed by a second wall which intersects it, as well as one 

 of the lateral walls of the primary cover cell, so as to include a nearly triangular cell. 

 In this triangular cell there are later formed, as both Bruchmann and Lang showed, 

 a varying number of segments arranged spirally in the fashion of the segments of a 

 three-sided apical cell (fig. 13, F). The same thing occurs in Lycopodium (Treub 1). 

 I have also found a similar condition in the antheridium both of the Marattiaceae 

 and oi Equisetum. The last-formed triangular cell is the opercular cell (fig. 13, F, o). 

 From the prothallial tissue which adjoins the sperm cells are cut off flattened cells 

 which surround the sperm cells with a more or less definite layer of "mantle" cells. 

 The limits of the original cover cell are usually plainly visible in both longitudinal 

 and surface sections. 



THE ANTHERIDIUM OF BOTRYCHIUM. 



The antheridia in Botrychium occur only upon the dorsal surface of the gam- 

 etophyte, which is always monoecious. The first antheridia in B. virginianum (see 

 Jeffrey 1, page 8), form a small cluster which is not noticeably raised above the 

 general level of the prothallium, and from this primary cluster extends a single 

 median line of antheridia toward the apex of the gametophyte. Later this median 

 region becomes raised and forms a conspicuous ridge along whose crest the anthe- 

 lidia are borne. In B. lunaria, according to Bruchmann, the arrangement is 

 much the same. 



Fig. 14. — Development of the antheridium in Botrychium virginianum. 

 A-D. Longitudinal sections of young antheridia. X320. 



E-H. Transverse sections. F, G show only the young spermatocytes. H, surface view showing opercular 

 cell, 0. I, section of two ripe antheridia. X80. 



The development of the antheridium is very much like that of Ophioglossum. 

 The first division, as in the latter, is a periclinal one, separating the primary cover 

 cell from the mother cell of the spermatocytes. The divisions in the cover cell, 

 however, differ somewhat from those in Ophioglossum, in that periclinal walls 



