SEO'l'. 1 



CRYrTOGAMS 



4:55 



the elongating stalk. It has a spherical capsule whicli on rapturing splits into 

 four valves (Figs. 374, 375). No columella is formed in the capsule ; but in 

 addition to speres it always produces elaters, which, by their movements while 

 drying, scatter the spores. The stalk of the capsule is delicate. The wall of the 

 capsule (usually two or several cells thick) consists of cells with annular or band- 

 like thickenings, or the walls are uniformly thickened with the excejition of the 

 outermost walls. Dehiscence is dependent on the cohesive power of the water in 

 these cells causing the outer walls to bulge into the cavity. 



According to the position of the sexual organs and sporogonium the Junger- 

 manniaceae are divided into two groups. 1. In the Anakrogynae the apex is not 

 used up in the formation of the archegonia, and the sporogonia are situated on 

 the dorsal surface and are surrounded by a sheath-like outgrowth of the thallus 

 forming an involucre. To this group 



belong the thalloid forms {Pellia, IS 



Metzgcria) and others showing a' 

 transition to the frondose forms 

 {Blasia). 2. In the Akrogynae, on 

 the other hand, the archegonia and 





Fig. 37(i.— Part of a shoot of Frvllania 

 Tamarisci, seen from below, r. Dorsal 

 leaves with the lower lobes («■.«) modilied 

 as water-sacs ; a, ami^higastriuni. ( x 

 36.) 



Fig. STT. — Haplomitriuin Hooke.ri. a, On'tjin of 

 a new shoot ; r, rhizome ; 0, lower limit of 

 the aerial shoot. (After Gottische.) 



the sporogonium stand at the end of the main stem or of a branch and are 

 surrounded by a perianth formed of modified leaves. To this group belong the 

 dorsiventral leafy forms, e.g. Plagiochila (Fig. -375), FruUania, and Jungermannia, 

 a genus with numerous species, 3. The Haplomitrieae ("S) hold an isolated 

 position but appear to exhibit the closest connection with the Anakrogynae. 

 This order contains only two genera, Calohryum, occurring in the tropics, and 

 Haplomitrmm. The single species of the latter genus, H. Hookeri (Fig. 377), 

 occurs in Europe, and possibly is a survival of preglacial Liverworts. The 

 Calobryaceae differ from all other Liverworts in the radial construction of their 

 shoot, which bears three rows of leaves. The sexual organs form terminal groups 

 in Calobryxcm, in Hai)lomitriuvi they occur between the upper leaves. 



