XI. HEPATIC^E. 933 



of a higher vegetation are gradually established ; Cyperacece and Graminea at first, then Vaccinium, 

 Myrica, dwarf Willows, and at last Pines, Birchen, &c. 



Some species of Sphagnum which abound in the Polar swamps serve as food to the reindeer. 

 Mingled with reindeer's hair they are used for stuffing mattresses. Sphaynum is frequently used in our 

 hot-houses in the cultivation of certain epiphytal Orchidece, to which it serves as it weie for soil by 

 keeping their roots always moist. 



XI. HEPATIC^E, Jutsiev, Bischo/, Nees v. Esenb. 



Cellular Acotyledons, either stemless with creeping often dichotomous fronds, 

 furnished or not with nerves ; or with leafy stems. REPRODUCTIVE ORGANS antheridia 

 and archegonia. ENVELOPE of the fruit (calyptra) rupturing at the top, and persistent 

 at the base of the pedicel. SPORANGIA capaular, usually 4-valved, nearly always accom- 

 panied by elaters. SPORES very numerous. 



Small annual or perennial, usually very delicate PLANTS, composed of a cellular 

 tissue, generally prostrate, rooting, inhabiting shady and damp places. FRONDS 

 green, violet or brown, sometimes expanded as membranous plates, foliaceous, 

 lobed, stomatiferous, nerveless, or traversed by a nerve formed of elongated cells ; 

 sometimes furnished with a simple or branched leafy axis. LEAVES membranous, 

 usually distichous, often entire, lobed or dentate, sometimes deeply divided, fre- 

 quently accompanied by accessory stipulary leaves named stipules or amphigastria. 

 ROOTS of simple fibres, tubular, white brown or purplish, transparent, scattered or 

 in small tufts, and springing from the lower surface of the fronds, sometimes from 

 the base of the amphigastria. 



The REPRODUCTIVE ORGANS are monoacious or dicecious, sometimes sunk in the 

 thickness of the frond (Riccia, &c.) ; sometimes projecting above the frond, and 

 often pedicelled (Marchantia) . ANTHERIDIA oblong or spherical, formed of a single 

 layer of transparent cells ; they contain a mucilage which becomes organized into 

 discoid very small and delicate cells ; when ripe, the antheridia rupture, or dehisce 

 transversely at the top, and expel a large number of these discoid cells, whence 

 come out, after a few seconds, filiform antherozoids, coiled in a spiral, and bearing 

 at their extremity two excessively slender threads. 



The ARCHEGONIA precede the appearance of the perianth, and are usually 

 found collected at the top of the principal axis, or of the lateral branches, or at the 

 axils of the amphigastria (Calypogeia, Mastigobryum) ; they are usually enclosed in 

 a peculiar organ resembling a wide-mouthed cup ; they are cellular sacs, usually 

 narrowed into a styloid process, channelled throughout their length, which, at a 

 certain period, ruptures at the top to admit the action of the antherozoids. The 

 broadest part of the sac contains one cell larger than the rest, the nucleus ; soon the 

 nucleus is divided in two by a horizontal septum ; the lower half forms the pedicel 

 (seta), which, when the capsule is ripe, is usually white and transparent, often very 

 short, and which by pushing the sporangium before it, ruptures irregularly the 



