BRYOPHYTA. 



701 



elongation of the axis of the female shoot takiiio; place in the region immediatelj' 

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

 though this stalk is no part of the sporogonium {cf. fig. 397 '*). 



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



AndreceacecB. — A small family, including the single genus, Andrecea. 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 pecuhar amongst Mosses. Four longitudinal slits 



Fig. 398.— Mosses. 



1 A germinatu!; spore. ' A Moss-protonema. ' Protonema giving rise to a bud from which will arise a leafy moss-shoot. 

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

 ' Tip of a female shoot with archegonia; two of them cont.ainiug spurogoniums have eularged. and in the left-hand one 

 of these two the upper part of the archegoniuni (calyptra) has been torn from the basal portion. » Leafy female 

 Btaoot bearing a fully developed sporogonium; the calyptra is still in position. ', -, ' x 350-400; * x 1.^: ' x SO; « x 6. 



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

 {cf. fig. 397 "). 



Bryacece. — 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 (ef. fig. 398 3). The curious properties of the 

 protonema of the Luminous Moss (Schistostega osmundacea) 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, £is a 

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



