46 MOSSES AND LIVERWORTS 



trivial detail may act as a clue to the correct 

 naming of some particular plant : an illustration 

 of the fact which is constantly impressed upon 

 us in the study of any branch of natural-history 

 and which applies with special force to the 

 moss world that no point, however small, is too 

 trivial to he taken account of. 



The Capsule. As the young spore-vessel in- 

 creases in size it gradually pushes off the veil, 

 and thus eventually we arrive at the fully de- 

 veloped spore-vessel, or capsule, the fruit of the 

 moss. In its earlier days the capsule is generally 

 green in colour, but as it ripens its hue changes 

 to warm yellow, brown, or crimson, and in its 

 mature stage it forms a very beautiful object for 

 microscopical examination, under a low-power 

 lens, and with a black background illumination. 

 Moreover, as we shall soon see, from the point 

 of view of its structure, and of the marvellous 

 adaptation of its various parts to the ends which 

 they are formed to serve, the interest of our story 

 culminates with the capsule. 



As may be supposed, the capsule varies greatly, 

 both in form and size, in the various species ; with 

 the help of Plates III., IV, IV.a, and IV.b, let 

 us take a glance at some of its most characteristic 

 aspects. Plate III. fig. 15 gives the long, narrow 

 capsule of our old friend the Wall Screw-moss 

 (Tortula muralis), that constant denizen of walls, 

 both brick and stone, and Plate IV.a, fig. 10, 



