MOSSES AND FERNS 



CHAP. 



until a short filament is formed. After a varying number of 

 transverse divisions an oblique wall is formed in the terminal 

 cell, and a second one nearly at right angles to it. By these 

 divisions the dorsiventral character is established, the first- 

 formed segment being ventral. A third oblique wall now 

 arises, intersecting both of the others, and the three include a 

 tetrahedral cell which is the permanent apical cell of the young 

 plant. The ventral segments do not at first form any trace of 

 leaf-like structures, and in the dorsal segments the leaves are at 

 first simple rows of cells; but a little later the leaves show 

 plainly their two-lobed character, each being made up of two 

 rows of cells united at the base. From the ventral segments 

 the amphigastria develop gradually, being quite absent in the 

 earlier ones. Chiloscyphits closely resembles Lophocolea, but 



FIG. 59. A, Germination of Lejeunia serpyllifolia; B, young plant of Radula com- 

 planata; x, the optical cell (all the figures after Goebel). 



the filamentous protonema is longer, and 1 is often branched. A 

 similar filamentous protonema is present in Cephalosia (Jun- 

 germannia) bicuspidata and other species. 



Lejeunia (Goebel (13) ) shows a most striking resem- 

 blance in its early stages to the simple thallose Jungerman- 

 niacese. The germinating spore forms either a short filament 

 or a cell surface (Fig. 59, A). In either case, at a very early 

 stage, a two-sided apical cell is established, and for a time the 

 young plant has all the appearance of a young Mctzgcria or 

 Aneura, This two-sided apical cell gives place to the three^ 

 sided one found in the older gametophyte, and the leaves and 

 stem are gradually developed as in Lophocolea. 



In Radula (Hofmeister (i), p. 55), and according to 



