MUSCI. 353 



SUBCLASS II. CELLULAR ACROGENS. 



Plants composed of cellular tissue only. Antheridia or archegonia, or both, formed 

 upon the stem or branches of the plant itself, which is developed from the germi- 

 nating spore usually with the intervention of a filiform or conferva-like prothallus. 



ORDER CXXVI. MUSCI. 



Low and mostly cespitose or tufted plants, caulescent and with distinct sessile 

 simple mostly 1 -nerved leaves, alternate in several ranks or rarely distichous, the 

 stems bearing spore-cases which contain only simple spores and open usually by a 

 deciduous lid. Inflorescence dioecious, monoecious, or bisexual, involucrate and 

 mostly bud-like, terminal or lateral, the reproductive organs accompanied by jointed 

 filaments (paraphyses). Male flowers (involucre, when present, called the peri- 

 ffonium) of several (1 to 20) clavate persistent antheridia, opening by an apical 

 slit and discharging a mucous fluid filled with oval cells, each containing an anther- 

 izoid. Female flowers (the involucre termed the perichcetium) of 1 to 20 flask-like 

 archegonia (or pistillidia), each inclosing a nucleus and terminated by a funnel- 

 mouthed tube (style), usually but one becoming fertilized, when the enlarging nucleus 

 bursts the envelope and elongates, the lower part forming a slender pedicel sheathed 

 by the base of the envelope (vaginule), the summit becoming a capsule bearing the 

 upper part of the archegonium as a calyptra. Capsule rarely indehiscent or dehis- 

 cing by 4 valves, usually opening by a lid (operculum), which leaves the mouth of 

 the capsule naked or surrounded by a ring (peristome) of usually 16 teeth, distinct 

 or coherent by pairs or more or less divided, with or without a variously divided 

 inner ring, the base of the peristome often encircled by an elastic ring of cells 

 (annuhis). The pedicel continues through the capsule as a columella, and is often 

 thickened under the base of the capsule, forming a collum (or apophysis) or, if only 

 at one side, a struma. The calyptra either splits at one side (becoming cucullate, or 

 dimidiate if cleft to the apex), or remains entire and campanulate or mitre-shaped 

 (mitriform). The sporangium lines the cavity of the capsule and contains the spores, 

 which are formed by fours within mother-cells. Spores in germination producing a 

 confervoid branching prothallus, developing buds which become leafy stems. Propa- 

 gation also takes place by means of gemmae, or by detached leaf-buds, or by the 

 formation of a new prothallus from the roots or from the root-like hairs (rhizoids) 

 which often abound upon the stems. 



An order of perhaps 150 genera and nearly 4,000 species, distributed over the entire globe, but 

 most abundantly in temperate and cooler regions. They love especially damp or shaded places, 

 and are found upon rocks, trees, the ground, or in running streams, each genus or species having 

 its peculiar preference. They vary much in size, from stems \ of a line to 1 or 2 feet in length, 

 but in diameter only from ^ to \ of a line. The stem is composed of more or less elongated 

 and narrow cells, the outermost layers usually much thickened and of a bright red or reddish 

 color. It is occasionally stoloniferous at base, more frequently branching above and extending by 

 a series of vigorous lateral shoots or innovations. The leaves are formed usually of a simple layer 

 of cells, with commonly a medial vein or costa, consisting of several layers. The tissue (nreolaMon) 

 of the blade is homogeneous in each layer, though the cells may vary much in form and size in 

 the same leaf, being usually larger and more elongated toward the base, as well as thinner and 

 destitute of chlorophyll. Cells which are placed end to end are said to be jn-osencfiymatous ; those 



