Ill 



THE JUNGERMANNIALES 



^S 



Elatereae 



Aneiira and Metzgeria represent the simplest of the typical 

 anacrogynous Jungermanniales. In the former the thallus 

 is composed of absolutely similar cells, all chlorophyll-bearing, 

 and in each cell one or more oil bodies, like those of the Mar- 

 chantiacese. In Metzgeria (Fig. 37) the wings of the thallus 

 are but one cell thick, and there is a very definite midrib, usu- 

 ally four cells thick. The apical growth in both genera is 



Fig. 37. — Metzgeria pubescens. A, Surface view of the thallus in process of division, 

 X80; B, growing point of a branch showing the two-sided apical cell (.r) and the 

 ventral hairs (h), X240; C, the growings point in process of division, x, x', the 

 apical cells of the two branches, X480. 



the same, and is effected by the growth of a ''two-sided" 

 apical cell.^ The segmentation is very regular, especially in 

 Met!:geria (Fig. 37), where each of the segments divides first 

 into an inner and an outer cell, the former by subsequent divi- 

 sions parallel to the surface of the thallus producing the thick- 



^Leitgeb (7), vol. iv. 



