306 EVANS. 



The gemmae which are first produced are strictly marginal, and in 

 their development a marginal cell becomes directly the mother cell of 

 the gemma. After the gemmae have been set free the empty mother 

 cells with their ruptured outer walls can easily be demonstrated, and 

 sometimes long and continuous stretches of such empty cells are 

 present, indicating a copious formation of gemmae. Later on, with 

 the narrowing of the gemmiparous branches, the cells of the sub- 

 marginal row may in turn give rise to gemmae, setting them free 

 dorsally. Apparently, however, the alar cells within this row and the 

 cortical cells of the costa do not have this power. 



The gemmae when set free are plane or slightly convex bodies, 

 always small and relatively simple, yet varying somewhat in size and 

 in the number of their component cells (Fig. 8, E, F). Most of them 

 are orbicular to oval in outline, measuring 0.1-0.12 mm. in length by 

 0.09-0.1 mm. in width and being usually four cells across. A single 

 apical cell is present and the stalk cells, although normally two, are 

 often indistinct. On each side three or four short marginal hairs, borne 

 singly and slightly displaced to the concave surface, can be detected ; 

 these are sometimes spreading and sometimes extend at right angles 

 to the surface of the gemma. Upon germination the marginal hairs 

 elongate, and the apical cell resumes its growth, giving rise to a flat 

 thalloid extension only two or three cells wide and thus narrower 

 than the gemma itself. In the case illustrated (Fig. 8, G) this exten- 

 sion had grown to more than twice the length of the gemma and had 

 produced a series of scattered marginal hairs, slightly displaced to one 

 surface. No later stages of germination have been observed. 



9. Metzgeria violacea (Ach.) Dumort. 



Jungermannia violacea Ach.; Weber & Mohr, Beitr. Naturk. 1: 76. pi. 1, 



f. 1-3. 1805. 

 Fasciola violacea Dumort. Comm. Bot. 114. 1822 (in part). 

 Echinogyna violacea Dumort. Syll. Jung. 84. 1831 (in part). 

 Echinomitrium violaceum [Echinomilrion violasceus] Corda; Sturm, Deutschl. 



Flora 2: 81. pi. 22. 1832 (in part). 

 Echinomitrium [Echinomitrion] furcalum 5. violaceum Hiiben. Hep. Germ. 



47. 1834 (in part). 

 Metzgeria violacea Dumort. Recueil d'Obs. sur les Jung. 26. 1835 (in part). 

 Metzgeria furcata 8. 2. violacea Nees, Naturg. Europ. Leberm. 3: 489. 1838 



(in part). 

 Metzgeria conjugata var. 0. violacea Lindb. Acta Soc. F. et^Fl. Fenn. 12: 



34. 1877. 

 Metzgeria angusta Steph. Bull. Herb. Boissier 7: 944. 1899 (in part). 

 Metzgeria antarctica Steph. Sp. Hepat. 6: 47. 1917. 



