in 



THE JUNGERMANNIALES 



105 



leavei, make them conspicuous. At the base of each of the 

 leaves is a long-stalked antheridium, large enough to be readily 

 seen with the naked eye. 



The development of the antheridium may be easily traced 

 by means of sections made parallel to the surface of the branch. 

 At the apex (Fig 50, C) is an apical cell much 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 



Fig. 52. — Porella Bolanderi. Successive stages of the young antheridium in median 

 longitudinal section, X6oo. 



of the leaves, close to where they join the stem, and are recog- 

 nisable in the fourth or fifth youngest leaf (Fig. 50, 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 of the antheridium, and the other the stalk. 

 The first wall in the antheridium itself is vertical (Fig. 52, B), 

 and divides it into two equal parts. Each of these is now 

 divided by two other intersecting walls, best seen in cross-sec- 



