AN OLD WALL 



But the extraordinary beauty of such a wall is only visible 

 when one peers and scrutinizes the surface very slowly and 

 carefully with the eyes six or seven inches away from it. 



In doing this, one is often troubled by rude and ribald 

 boys. A botanical friend indeed complained that he had 

 been for months avoided and shunned as a dangerous wander- 

 ing lunatic on account of his botanical enthusiasm. But 

 true botanists get accustomed to disagreeable incidents like 

 that, and pay no attention to the vulgar crowd. 



The change in an old wall when one looks at it from a few 

 inches distance is most remarkable. The entire surface is 

 spotted or dusted, sprinkled or entirely covered by thick 

 lichen stains and crusts. 



The original colour of the stone is nowhere visible. The 

 lichens show the most delicate shades and contrasts in colour ; 

 all pleasing and all blending together in harmonious general 

 tones. The fruit of these lichens is like a minute saucer or 

 platter generally with a thin rim or border, but it is exceed- 

 ingly small, probably only one-sixteenth of an inch in 

 diameter, or even less. The smallest of these crust lichens 

 form continuous, very thin, coatings, covering the stone ; 

 and against this background the little saucer -like fi-uits 

 show up quite distinctly. 



The coating itself varies from " bright yellow, pale ochre, 

 citron, chestnut colour, to mouse colour, different shades of 

 grey and green, cream colour, lead colour, blue-black or pure 

 black, tawny, brown, rusty red or pure white." The cups of 

 one kind {Lec'idea^) are black, whilst those of Lecanora are 

 generally reddish-brown. But they may be a ghostly pale 

 hue which stands out plainly against the grey-green back- 

 ground of the frond. 



1 Lecidea has at least 230 species on British stones and rocks (Leighton). 



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