ACROGEN^. 



715 



they are not used in medicine. The species of Sphagnum fur- 

 nish food to the reindeer, and even to man in the polar regions. 

 Natural Order 291. Hepaticace^.— The Liverwort Order 

 {figs. 1093 and 1094).— (See pages 370— 372).— Character.— 

 Small cellular plants, either with a creeping stem bearing minute 



Fig. 1093. 



1094. 



Fig. 1093. Jimgermannia bidentata. 

 The stem is "creeping, and liears 

 numerous small inibrirated leaves. 



. Fig. 1094. Sporangium of Jnn- 



germannia hyalina, dehiscing ver- 

 tically by 4 valves, and contaiuiug 

 spores iu its interior. 



imbricated leaves {fig. 1093), or with a lobed leaf-like frond or 

 thalloid expansion {figs. 811 and 813). Bcprocluctive organs 

 of two kinds, called antheridia and archegonia, which are 

 either on the same plant or on diiferent ones. The anth- 

 ridia are small, oval, globular, or flask-shaped cellular sacs {fig. 

 812), situated in the axils of leaves, or immersed in the frond, 

 or imbedded in the upper surface of peltate or discoid-stalked 

 receptacles {fig. 811). Th.e archegonia {fig. 814) are usually 

 somewhat flask-shaped bodies, which are imbedded in the fronds, 

 or contained in receptacles {fig. 813, r) elevated on stalks {fig. 

 813, s) above the thallus. Each archegonium developes after 

 fertilization a sporangium, which either bursts by valves {fig. 

 1094), or by teeth, or by irregular fissures. The sporanginm is 

 usually without a columella, and contains spores mixed with 

 elaters {fig. 815) ; or it is furnished with a thread-like colu- 

 mella, and contains spores and no elaters, or the latter are 

 imperfect ; or it has neither elaters or columella. 



Division of the Order, and Examples of the Genera. — This 

 order may be divided as follows : — 



Sub-order 1. Jungermanniacem or JungermanniecB. — Scale- 

 Mosses {figs. 1093 and 1094). — Sporangia oval ; without a 

 columella ; splitting vertically by 4 valves {fig. 1094). Spores 

 mixed with elaters. Examples : Blasia, Jimgermannia. 



Sub-order 2. Anthocerotea. — Sporangia pod-shaped; 1 — 2- 



