FLORA. 165 
forms are wonderfully varied ; so that they present to the 
student of Nature an almost inexhaustible field of inquiry. 
Tn their most rudimentary aspects they seem to consist of 
nothing more than a collection of powdery granules, so 
minute that the figure of each is scarcely distinguishable, 
and so dry and so deficient in organisation that we cannot 
but wonder how they live and maintain life. Now they 
are seen like ink-spots on the trunks of fallen trees; now 
they are freely sprinkled in white dust over rocks and 
withered tufts of moss ; others appear in gray filmy patches ; 
others again like knots or rosettes of various tints; and 
some are pulpy and gelatinous, like aérial sea-weeds which 
the receding tide leaves bare and naked on inland rocks. 
A greater complexity of structure, however, is visible in 
the higher order of lichens—and we find them either 
tufted and shrubby, like miniature trees ; or in clustering 
cups, which, Hebe-like, present their “dewy offerings to 
the sun.” 
‘In the Polar world, and its regions of eternal winter, 
where snow and ice, and dark drear waters, huge glacier 
and colossal berg, combine to form an awful and impressive 
picture, the traveller is thankful for the abundance of 
these humble and primitive forms, which communicate the 
freshness and variety of life to the otherwise painful and 
death-like uniformity of the frost-bound Nature. 
‘A lichen which is discovered in almost every zone of 
altitude and latitude, which ranges from the wild shores of 
Melville Island in the Arctic to those of Deception Island 
in the Antarctic circle,—which blooms on the crests of the 
Himalayas, on the lofty peak of Chimborazo, and was 
found by Agassiz near the top of Mount Blanc,—is the 
Lecidea geographica, a beautiful bright-green lichen, whose 
clusters assume almost a kaleidoscopic appearance. 
‘A lichen of great importance in the Arctic world is the 
well-known Cladonia rangiferina, or reindeer moss, which 
forms the staple food of that animal during the long Arctic 
winter. In the vast tundras, or steppes, of Lapland, it 
flourishes in the greatest profusion, completely covering 
