THE ARCHEGONIAT^E 



233 



ceases, and the subsequent growth of the sporophyte is basal, much as in 

 Anthoceros. 



An early division of the tissues into endothecium and amphithecium 

 is apparent, but the archesporium is derived from the outer layer of 

 the endothecium, and not from the amphithecium as in Sphagnum. 

 The archesporium is restricted to a relatively small part of the 

 sporophyte. In the aberrant genus Archidium no definite arche- 

 sporium is developed, but otherwise the sporophyte conforms to the 

 usual type. 



As the sporophyte develops, the upper part enlarges and forms the capsule 

 (Fig. 197). This enlargement is in part due to increase in the number of cells, 

 partly to the development of a large air-space between them. This space arises 



FIG. 196. Funaria hygrometrica. Five transverse sections of a young embryo. 

 A, just below the apex ; the others successively lower down (X 450). 



in the amphithecium, and is separated from the archesporium by two or three 

 layers of cells. Some of the cells remain in contact, and elongate as the space 

 enlarges, and form alga-like filaments extending across it. These cells, as well 

 as those outside the space, contain numerous chromatophores. The lower por- 

 tion of the capsule does not develop any sporogenotis tissue, but forms a mass 

 of green parenchyma, often with conspicuous air-spaces, and constituting the 

 principal assimilating part of the sporophyte. In the higher Mosses this 

 "Apophysis" has perfect stomata (Fig. 198) developed in the epidermis. 



The lower part of the sporophyte forms a slender stalk or seta, which termi- 

 nates below in a more or less well-developed foot. The endothecium in the seta 

 develops into a definite central strand of conducting tissue, suggesting the vas- 

 cular bundles of the higher plants. 



The archesporium forms a cylindrical layer about the central columella of the 

 capsule, but does not extend over it. The upper portion of the capsule becomes 

 the lid or " Operculum," which is found in most but not all Bryales. Where 

 the operculuui joins the Theca, or spore-bearing part of the capsule, the latter 



