BY L. RODWAY. 7 



even sometimes from the sporogonium, it probably has 

 little philogenetic interest. 



The shoot may be simple or branched, but always bears 

 leaves. These organs are generally one cell thick, but may 

 have one or two thicker nerves, but no lateral veins. The 

 surface may be increased by erect plates or papillae upon 

 the upper surface, or by a papillose condition of the cells, 

 but no cuticle or stomata are present. 



In Sphagnum the antheridia are globose, stalked, and 

 produced singly in the leaf axils of specialised branches. 

 In all others they are flask-shaped, and may be terminal or 

 lateral, according to species. The archegonia terminate 

 the axis, or, in other cases, may be lateral upon verv dwarf- 

 ed lateral branches. The leaves surrounding the arche- 

 gonia become enlarged into a perichaetium. The arche- 

 gonial neck is long. The embryo sends an absorbent foot 

 into the tissue of the parent, and its upper portion develops 

 into a capsule. In most mosses between the foot and the 

 capsule there is formed an elongated seta. The base of the 

 archegonium may also grow into a short column, the vagi- 

 nule, at the base of the seta. In Andrcaea and Sphagnum 

 there is little or no seta, but the capsule is carried up on a 

 prolongation of the axis, the pseudopodium. 



In a few primitive mosses all the internal cells of the 

 capsule develop into spores or become disorganised. A 

 steady sterilisation of tissue accompanies advance in type. 

 In Sphagnum and Andreaea the centre remains as perma- 

 nent tissue to form the columella, and a bell or dome- 

 shaped band of tissue alone forms spores. In the higher 

 mosses the apex of this also becomes sterile, and the arche- 

 sporium is reduced to a narrow cylinder or band. When 

 the sj^orogoniuin elongates it ruptures the wall of the arclie- 

 goniuni near the base, and carries it up as a hood, the 

 calyptra. 



The capsule and seta, as maturity advances, become 

 tough and of persistent quality. In some primitive forms 

 the capsule does not burst, but' depends upon rotting for 

 spore dispersal. In Andrcaea the escape of spores is effect- 

 ed by the capsule opening by four or more longitudinal 

 slits. In all others special provision is made for dispersal 

 at the top of the capsule. A lid is formed, which falls off 

 at maturity. This is often assisted bv a ring of hygroscopic 

 cells, the annulus, formed at the junction of lid and capsule. 

 The mouth may be open or closed by a membrane, or, more 



