DEVELOPMENT OF PLAXTS 



271 



spore germinates very much as the Anthoceros (Fig. 203, 6). 

 It does not, however, have as prolonged a growth, and at ma- 

 turity consists of a well developed foot embedded in the tissues 

 of the gametophyte and a spore-bearing capsule (Fig. 203, $A). 



Fig. 203. The sporophyte of Sphagnum: 6, the young sporophyte sepa- 

 rated from the archegonium with essentially the same differentiation of 

 parts as noted in Anthoceros, Fig. 199. 5A, diagram of a later development 

 of the sporophyte in the archegonium. The enlarged foot, b, is embedded 

 in the apex of the moss branch, p, and the spores, sp, form a dome-shaped 

 layer in the upper part of the capsule. 5, the naked stem, p, of the moss 

 branch, surrounded at base with spirally arranged leaves, has elongated, 

 lifting the mature sporophyte into the air. The enlargement of the stem, 

 b, is due to the growth of the foot region of the sporophyte ; ca, remains 

 of the ruptured archegonium or calyptra ; 0, lid or operculum of the cap- 

 sule. — After Schimper. 



The stomata and chlorenchyma which were so conspicuous in 

 Anthoceros are less perfectly represented, but the spore mother 

 cells are still developed in a dome-shaped zone. This rather 

 minute sporophyte at maturity barely breaks through the arche- 

 gonium, known in this condition as the calyptra, which covers 

 the capsule as a cap. The absence of a conspicuous stalk or seta 

 in the sporophyte of Sphagnum is provided for by the elongation 

 of the upper part of the moss stem which pushes the sporophyte 



