GROUP ii. BRYOPHYTA: MUSCI. 341 



The Sphagnacese have no special organs for vegetative propagation; 

 but they multiply vegetatively by the dying away of the main stems so 

 that the lateral branches become separate and constitute distinct plants ; 

 consequently these plants are found in considerable masses. They in- 

 habit damp, boggy spots, and retain a considerable quantity of water 

 in the open cells of the branches and leaves. Masses of Sphagnum thus 

 saturated with water form peat-mosses or peat-bogs, the water being 

 raised to the surface by means of the capillary system formed by the open 

 cells. 



B. The SPOROPHYTE. The oospore, as in other Mosses, is divided by the 

 transverse basal wall into an epibasal and hypobasal half. The epibasal 

 half gives rise to the capsule : it grows at first apically, segments being 

 formed by transverse walls, each segment being divided into four cells 

 (quadrants) by walls at right angles to each other: after six or eight 



FIG. 20(5. Longitudinal section (diagram- 

 matic : x 19) of the sporogonium of Spbag- 

 num : p* pseudopodium ; / foot ; c calyptra 



FIG. 205. Part of shoot of Sphagnum with neck of archegonium h ; a* arche- 



icutiwl iiun (nat. size). /: Capsules. Bporium. 



segments have been formed, apical growth ceases, the further growth 

 being intercalary. The cells of each segment become differentiated each 

 into an external and an internal cell; the external cells constitute the 

 amphithecium, the internal cells the endothecium. The amphithecium 

 comes to consist of several layers by periclinal divisions, the first formed 

 and most internal layer constituting, in its upper half, the archesporium ; 

 the endothecium constitutes the columella. Thus the archesporium is a 

 hollow hemisphere which covers the columella as a cap. There is no 

 intercellular cavity formed in the capsule. 



The hypobasal half of the oospore undergoes but few divisions, forming 

 a bulbous foot, the superficial cells of which grow out into short) 

 papillse. 



The fully developed sporogonium consists of a capsule attached to the 

 foot by a very short seta ; the wall of the capsule consists of a single 



