MOSSES 17 



the leaves, and, these being specially long, the 

 hoary appearance of the cushion-like tufts is still 

 more noticeable. At Plate VII. fig. 31 will be 

 found an enlarged drawing of a leaf of one of 

 these plants. The Silvery Thread-moss (Bryum 

 argenteum), one of the lowliest members of the 

 great Thread-moss (or Bryum) family, often grows 

 in great abundance on walls, and, like the 

 Wall Screw-moss above mentioned, will not be 

 deterred even by the close proximity of a large 

 manufacturing town. The plant from which the 

 illustration given at Plate II. fig. 12 was made 

 was gathered from a wall in a suburb of Birming- 

 ham, within a comparatively short distance from 

 the centre of the city. This moss is easily 

 recognised by its white, silvery appearance 

 (whence its name), a feature which is due to 

 the delicate and colourless leaves, considerable 

 portions of which, when examined under the 

 microscope, will be seen to be altogether devoid 

 of the green colouring matter or chlorophyll, to 

 which leaves in general owe their green tint. 



There are various other members of this same 

 Bryum family that are frequent inhabitants of 

 walls, many of them having much larger leaves, 

 and producing an abundance of pear-shaped spore- 

 vessels, which form very conspicuous objects in 

 the spring or early summer, when their warm red 

 colour denotes that they are full of ripe spores. 

 In some parts of the country, as, for instance, in 



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