IV 



THE JUNGERMANNIACE.^ 



99 



like that in the sterile branches, but with the outer face 

 more convex. The divisions in the segments are the same 

 as there, but the whole branch remains more slender, 

 and the hairs at the base of the leaves are absent. The 

 antheridia arise singly from the bases of the leaves, close to 

 where they join the stem, and are recognisable in the fourth or 

 fifth youngest leaf (Fig. 42, C, $ ). The antheridial cell 

 assumes a papillate form, and divides by a transverse wall into 

 an outer and inner cell, and the former divides by a similar 

 wall into two cells, of which the upper one is the mother cell 



Fig. 43. — Diagram showing the ordinary method of branching in the acrogynous Jungermanniacese 

 (after Leitgeb). D, Dorsal ; V, ventral part of stem ; X' X", apical cells of the branches. The 

 segments are numbered. 



of the antheridium, and the other the stalk. The first wall in 

 the antheridium itself is vertical (Fig. 44, B), and divides it 

 into two equal parts. Each of these is now divided by two 

 other intersecting walls, best seen in cross-section (Fig. 45, A), 

 wdiich separate a central cell, nearly tetrahedral in form, from 

 two outer cells. In the complete separation of the central 

 cell by these first two walls, Porella appears to differ from the 

 other Jungermanniaceae examined,^ where these first two 

 peripheral cells do not reach to the top of the antheridium, 



1 Leitgeb (7), vol. ii. p. 44. 



