BRYOPHYTA. 



701 



elongation of the axis of the female shoot taking place in the region immediately 

 below the group of archegonia. The capsule is thus hoisted up on a long stalk, 

 though this stalk is no part of the sporogonium (c/. fig. 397 ^^). 



The remains of the Bog-mosses form an important constituent of peat. 



AncirewacecB. — A small family, including the single genus, Andreoea. They are 

 amongst the first settlers upon new and inhospitable rock-surfaces, and play an 

 important part as soil-formers (cf. vol. i. p. 266). In them the mode of bursting of 

 the spore-capsule is altogether peculiar amongst Mosses. Four longitudinal slits 



rig. 398. — Mosses. 



1 A germinating spore. 2 a Moss-protoneraa. s Protonema giving rise to a bud from which will arise a leafy moss-shoot. 

 * Longitudinal section of the tip of a male shoot of a Moss ; small, club-shaped antheridia are present between the scales. 

 5 Tip of a female shoot with archegonia ; two of them containing sporogoniums have enlarged, and in the left-hand one 

 of these two the upper part of the archegonium (calyptra) has been torn from the basal portion, s Leafy female 

 shoot bearing a fully developed sporogonium ; the calyptra is still in position. 1, 2, s x 360 - 400 ; < x 16 ; » x 80 ; « x 6. 



arise in its wall, and the four valves remain attached to one another at the apex 

 {cf. fig. 397 18). 



BryacecB. — This family includes the vast majority of the Mosses. The germinat- 

 ing spore produces a simple, branching, filamentous protonema (figs. 398 ^ and 398 ^) 

 on the surface of the ground, certain of its branches developing as colourless 

 rhizoids and penetrating the substratum. From the protonema the ordinary leafy 

 Moss-plant arises as a lateral bud {cf. fig. 398^). The curious properties of the 

 protonema of the Luminous Moss {Schistostega osmundaoea) have been already 

 described {cf. vol. i. p. 385, and PI. I. fig. p). The leafy shoots become rooted by the 

 development of rhizoids from their lower extremities, and bear their leaves, as a 

 rule, in three rows, though a slight twisting of the stem often disguises this fact. 



