24 



THE OPHIOGLOSS \l I - 



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, />), and this is followed by a second wall which intersects it, as well as one 

 of the lateral walls ol 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 ol segments arranged spirally in the fashion of the segments of a 

 three -si ded apical cell (fig. 13, F). I he same thing occurs in Lycopodium ( Treub I ). 

 Phavc also found a similar condition m the antheridium both of the Marattiaceae 

 and of Equisetum. The last-formed triangular cell is the opercular cell (fig. 1 .;,/-, 0). 

 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 or BOTRYCHIUM. 



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

 etophyte, which is always monoecious. I he hist antheridia in />'. virginianum (see 

 [effrey I, page M), 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 gametophvte. Later this median 

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

 1 ul 1:1 are borne. In H. lunaria, according to Bruchmann, the arrangement is 

 much the same. 



In.. 14. — Development of tin- antheridium in Botrychium virginianum. 



\ |). Longitudinal sections of young antheridia. ■ ;;o. 



E II. Transverse sections. 1', O show only the youngs] rl f surface view showing opercular 



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



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



I In fust division, as in the latter, is a pcriclinal one, separating the primary cover 



cell from the mother cell of the spermatocytes. I he divisions in the cover cell, 



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



