CHAPTER V 



ROCK LICHENS 



When passing along a sheltered winding road a very 

 unusual colour may be sometimes seen on the old walls 

 or dry stone dykes. 



It is particularly noticeable when the sun's rays 

 strike along the wall, as happens late in the afternoon 

 in autumn ; then the irregular stones seem to glow with 

 an unearthly colouring which is quite unlike any other 

 of Nature's effects and is most impressive. 



It is not easy to find a word which will exactly 

 express the shade, though perhaps golden-tawny or 

 russet-orange may give a faint impression of it ; but it 

 is not a flat but a velvet-like covering which touches 

 up the surfaces and extends into the crevices and 

 recesses between the stones.-^ 



When one examines the wall carefully, one finds a 

 brown fluff scarcely yVth of an inch in thickness, and 

 which is even more exquisitely beautiful when seen 

 under the microscope. This is a minute tufted Alga 

 chroolepus or trentepohlia.-^ One wonders if there is 

 any microscopic eye belonging to some artistic insect 

 which is capable of enjoying such an exquisite little 

 plant. This is not unlikely, for these chroolepus have 

 a faint yet agreeable perfume, in which respect no other 

 algae resemble them. The ordinary '< forgotten " 

 seaweed smell is one of the most abominable in the 

 world. 



Small insects can be seen wandering over the velvet 



63 



