490 



BOTANY 



their structure is correspondingly various. Close tufts or masses are especially 

 characteristic of dry habitats, while the typical inhabitants of the soil of woods 

 have a looser mode of growth. In the moist mountain forests of the tropics and 

 sub-tropics Mosses often grow in considerable masses surrounding the branches or 

 hanging in long veil-like masses from them ( 105 ). 



The Bog-Mosses form extensive growths on moors, as also do others (especially 

 Polytrichum] on the moist soil in the arctic moss-tundras. 



The profusely-branched protonema of the Mosses appears to the 

 naked eye as a felted growth of fine, green filaments (Fig. 432). 



f^ 



c 



FIG. 452. Sphagnum fimbriatum : A, A shoot with four ripe sporogonia. Sphagnum squarrosum: 

 B, A lateral shoot with a terminal sporogonium ; ca, ruptured calyptra ; (/., operculum. 

 Sphagnum acutifoliurn : C, a young sporogonium in longitudinal section ; ps, pseudopodium ; 

 ca, archegonial wall or calyptra ; ah, neck of archegonimn ; spf, foot of sporogonium ; k, 

 capsule ; co, columella ; spo, spore-sac with spores. (/J and after W. P. SCHIMPER ; A, nat. 

 size ; the other figures magnified.) 



The oblique position of the cell walls in the filaments is characteristic. 

 The young moss plants are developed on the protonema as small 

 buds which arise as protrusions of cells of the filament, usually from 

 the basal cell of one of the branches. The protrusion is cut off by a 

 transverse septum, and after the separation of one or two stalk-cells 

 the three-sided pyramidal apical cell of the moss plant is delimited 

 in the enlarged terminal cell ( 106 ). The moss plants are always 

 differentiated into stem and leaf. The Mosses may be readily dis- 

 tinguished from the foliose Jurigermanniaceae by the spiral arrange- 



