Ill 



THE JUNGERMANNIALES 



"5 



Goebel, much the same condition occurs in Porella, the first 

 divisions of the spore give rise to a disc, and the formation of 

 a filament is completely suppressed. This disc is nearly circu- 

 lar in outline, and at its edge a single large cell appears (Fig. 

 59, B), whose relation to the primary divisions of the spore is 

 not quite clear. This cell forms the starting-point for the 



..b. 



FIG. 60. A, Lejeunia metzgeriopsis, showing the thalloid protonema with terminal 

 leafy buds (fc), Xi4 (after Goebel). B, Gemma of Cololejeunia Goebelii. 



growing apex of the gametophore. As in the other forms, the 

 first leaves are extremely rudimentary, and only gradually is 

 the complete gametophyte developed. 



How far this variation in the form of the protonema is of 

 morphological importance is a question, as the same species 

 may show both a filamentous protonema and the discoid form. 



