18 



THE OPHIOGLOSSALES 



The antheridia form a more or less evident row, even in the very young 

 prothallium, and later this median rovp of antheridia is raised upon an elevated 

 ridge, upon whose sides the archegonia later make their appearance (fig. 6, D). 



The gametophyte of B. lunaria closely resembles the early stages of B. virgin- 

 ianum. It is very much smaller and rarely exceeds a length of 2 millimeters, and, 

 like the young stages in B. virginianum, it is covered with many long rhizoids 

 (fig. 8, A, B.) The smaller prothallia are globular or oval in shape; the larger ones 

 somewhat heart-shaped. Hofmeister states that the antheridia occur upon the upper 

 surface and the archegonia below; but Bruchmann found that both archegonia and 

 antheridia were confined to the upper surface, as in B. virgtnianum. As in the 

 latter, also, the dorsal ridge is present, bearing the antheridia upon its crest and the 

 archegonia upon its flanks. 



The large prothallia of B. virginianum live for many years, and Jeffrey even 

 found a plant bearing spores, which was still connected with a prothallium. It is 

 probable that the very much smaller prothallia oi B. lunaria have a shorter duration, 

 but in this species also the prothallium persists for some time after the young 

 sporophyte is established. 



THE HISTOLOGY OF THE GAMETOPHYTE OF BOTRYCHIUM. 



In B. Virginianum the forward part of the prothallium is made up of colorless 

 tissue, which extends for some distance beyond the youngest antheridia. The apical 

 meristem in this species (fig. 6, E) lies on the upper side of the prothallium; in a 

 vertical longitudinal section it shows a group of columnar cells, one of which is 



Fig. 9. 



A. Transverse section of a gametophyte of Ophioglossum ftendulum, showing position of 



endophytic fungus. X20. The shaded region is occupied by the endophyte. 



B. Endophyte from prothallium of Boirychinin virgitiianum. 



C. Sporangium-like enlargements of endophyte. 



probably the apical cell; but this is not absolutely certain. In B. lunaria (see 

 Bruchmann 2, page 209) the apical meristem occupies the middle region of the 

 anterior surface of the prothallium, and is of very limited extent. As in B. vir- 

 ginianum, its cells appear columnar in form, but neither in longitudinal section nor 

 in a surface view could a single initial cell be recognized. 



The rhizoids in B. virginianum are from i to 4 millimeters in length and may 

 be niulticellular, especially those which arise from the crest and flanks of the pro- 

 thallium, while those which originate from the base are unicellular and longer than 

 these multicellular ones. It is not unlikely that these multicellular structures are 

 rather of the nature of paraphyses than true rhizoids. In B. lunaria the rhizoids 

 seem to be, usually at least, unicellular. In both species the rhizoids soon turn 

 brown and their walls become strongly curinized. Both Jeffrey and Bruchmann 



